There are 357 seniors in harris high schoo. The ratio of boys to girls is 7:10. How many boys are in the seniors class?
If a united startes dollar is worth 1.41$ in canadian money, how much is $100 in canadian money worth in united states money, to the nearest cent?
Solve the following system of equations:
3x+2y=4
-2x+2y=24
2007-09-13 14:46:54 · 10 answers · asked by gone 3 in Science & Mathematics ➔ Mathematics
147
$70.92
x= -4
y=8
2007-09-13 14:55:41 · answer #1 · answered by joem 2 · 0⤊ 2⤋
There are 357 seniors in harris high schoo. The ratio of boys to girls is 7:10. How many boys are in the seniors class?
7:10= 17
7/17 x 357= 147 boys.
If a united states dollar is worth 1.41$ in canadian money, how much is $100 in canadian money worth in united states money, to the nearest cent?
$1.41 Can= $1.00 US
$100.00 Can= (1.00/1.41)x100.00
= $70.92
Solve the following system of equations:
3x+2y=4 --- Eq. 1
-2x+2y=24 --- Eq. 2
From Eq. 1: 2y= 4-3x
Substitute 2y= 4-3x into Eq. 2
-2x+(4-3x)=24
-2x+4-3x=24
-5x+4-24=0
-5x-20=0
-5x= 20
x= 20/-5 = -4
If x=4, from Eq. 1:
3(-4)+2y=4
-12-4=-2y
-16=-2y
y= 8
Hope this helps.
2007-09-13 22:08:25 · answer #2 · answered by Starburst 1 · 0⤊ 0⤋
1)
Let x = # of boys
then 357 - x = # of girls
x / (357 - x) = 7 / 10
10x = 7 (357 - x) = 2499 - 7x
17x = 2499
x = 2499 / 17 = 147
There are 147 boys.
2)
1 US$ = 1.41 Canada$
100 C$ = 100/1.41 = 70.92 US$
3)
3x+2y = 4
-2x+2y = 24
5x = -20
x = -4,
2y = 4 - 3x = 4 + 12 = 16
y = 8
2007-09-13 21:58:52 · answer #3 · answered by vlee1225 6 · 1⤊ 0⤋
3. Solve for "x" or "y" in either equation. Let's solve for "y" in the 1st equation.
First: subtract 3x from both sides (when you move a term to the opposite side, always use the opposite sign).
3x-3x+2y = 4-3x
2y = 4 - 3x (Divide each term by 2).
2y/2 = 4/2 - 3x/2
y = 2 - 3x/2
SEc: substitute "2-3x/2" with "y" in the 2nd equation.
-2x+2(2-3x/2) = 24
-2x+2(2)+2(-3x/2) = 24
-2x+4 - 3x = 24
- 5x + 4 = 24
5x+4 - 4 = 24 - 4
-5x = 20
-5x/-5 = 20/-5
x = - 4
Third: substitute - 4 with "x" in the 1st equation.
3(- 4)+2y = 4
- 12+2y = 4
- 12+12+2y = 4+12
2y = 16
2y/2 = 16/2
y = 8
Solution (- 4, 8)
2007-09-13 23:37:36 · answer #4 · answered by ♪♥Annie♥♪ 6 · 1⤊ 0⤋
Question 1
No. of boys (7 /17) x 357 = 141
Question 2
Canadian $1.41<---->US $1
Canadian $100<-->(100 / 1.41) x 1 US $
$100 Canadian = $70.92 US
Question 3
6x + 4y = 8
-6x + 6y = 72-----ADD
10y = 80
y = 8
3x + 16 = 4
3x = - 12
x = - 4
x = - 4 , y = 8
2007-09-15 10:49:46 · answer #5 · answered by Como 7 · 1⤊ 0⤋
1. the ratio is like a fraction 7/10. multiply that by 357 and theirs your answer
2.100 divide 1.41
3. multiply one of the equation by -1 so u would cancel 2y by adding both equations like so:
-1(3x+2y=4)
or
-1(-2x+2y=24)
then add like terms down and find x
2007-09-13 21:55:50 · answer #6 · answered by philadelphia 3 · 0⤊ 2⤋
1) set up a proportion of boys/total students
2) There are 7+10 students or 17 total students.
3) The ratio would be boys/total SO 7/17=x/357
4) Cross multiply and divide.
Someone else can help with the other two.
2007-09-13 21:54:00 · answer #7 · answered by Ed S 4 · 0⤊ 2⤋
7boys/10girls+7boys = 7boys/17seniors = xboys/357seniors = 7boysX357seniors/17seniors = 2499boys/17 = 147boys
$1US/$1.41Canandian = xUS/$100Canadian =
$1US x $100Canadian/$1.41Canadian = $100US/$1.41 = $70.92US
3x + 2y = 4
-2x + 2y = 24
------------------
Wait - is that supposed to be -2x OR - (2x+2y)? Please clarify.
2007-09-13 22:10:43 · answer #8 · answered by javadic 5 · 0⤊ 0⤋
If there are B boys, then there are .7B girls.
B + .7B = 357
1.7B = 357
B = 357/1.7 = 210
100 Canadian*( 1 US / 1.41 Canadian) = 70.92 US
2007-09-13 21:55:13 · answer #9 · answered by fcas80 7 · 0⤊ 2⤋
147
$175.18
(20,-32)
2007-09-13 21:57:00 · answer #10 · answered by sweetfreak2 1 · 0⤊ 1⤋