find the number she has of each kind
2006-12-01 05:09:43 · 8 answers · asked by vanessa s 1 in Science & Mathematics ➔ Mathematics
10 quarters and 3 dimes.
10 x $0.25 = $2.50
3 x $0.10 = $0.30
$2.50 + $0.30 = $2.80
2006-12-01 05:15:43 · answer #1 · answered by whawkeyes06 2 · 0⤊ 0⤋
If we let Q be the number of quarters and D be the number of dimes, we know that
D = Q - 7
And we know that
0.10 D + 0.25 Q = 2.80
So we substitute D with Q - 7
0.10 (Q - 7) + 0.25 Q = 2.80
0.10 Q - 0.7 + 0.25 Q = 2.80
0.35 Q - 0.7 = 2.80
0.35 Q = 3.50
Q = 3.50/0.35 = 10
Since Q = 10, D = Q - 7 = 10 - 7 = 3
So Bess has 10 quarters and 3 dimes. 10 quarters and 3 dimes adds up to $2.80, so we're in the clear.
2006-12-01 05:18:14 · answer #2 · answered by Puggy 7 · 0⤊ 0⤋
The mathematical way to do this one is:
.10*d+.25*q=2.80
q=d+7 (the number of dimes is 7 less than the number of quarters)
now plug in d+7 for q in the first equation:
.10*d+.25*(d+7)=2.80
Multiply by 100 to get a simpler to solve equation:
10d+25(d+7)=280
Simplify:
10d+25d+175=280
35d=105
d=3
because q=d+7
q=10
so 3 dimes and 10 quarters
(d=dime)
(q=quarter)
2006-12-01 05:21:14 · answer #3 · answered by D 3 · 0⤊ 0⤋
10 quarters 3 dimes
2006-12-01 05:12:25 · answer #4 · answered by MeanKitty 6 · 0⤊ 0⤋
Who needs all that difficult algebra? Here's the easy way :-
Take away the 7 extra quarters = $1.75.
That leaves $1.05, to be made up with the same number each of dimes and quarters.
One dime and one quarter = $0.35, so we need that three times over.
Three dimes, three quarters, and the seven quarters we accounted for at the beginning makes three dimes and ten quarters altogether.
2006-12-01 07:54:31 · answer #5 · answered by Anonymous · 0⤊ 0⤋
First, set up an equation:
x = number of quarters
(x - 7) = number of dimes
Therefore,
0.25x + 0.10(x - 7) = 2.80 --- Multiply the 0.10 throughout the parentheses...
0.25x + 0.10x - 0.70 = 2.80 --- Combine like terms...
0.35x - 0.70 = 2.80 --- Add 0.70 to both sides...
0.35 = 3.50
x = 10
x - 7 = 10 - 7 = 3
ANSWER: There are 10 quarters and 3 dimes.
CHECK: 0.25(10) + 0.10(3) = 2.80
2.50 + 0.30 = 2.80
2.80 = 2.80 ---Answer checks out!
2006-12-01 05:19:44 · answer #6 · answered by Anonymous · 0⤊ 0⤋
This is a simple lesson in simultaneous linear equations.
D = number of dimes
Q = number of quarters
25Q + 10D = 280
and
D = Q - 7
So, substitute either D or Q from the second equation into the first equation, and solve the first equation for Q or D, and then plug that number into the second equation for whichever you did not solve for in the first.
Clear?
2006-12-01 05:16:10 · answer #7 · answered by themountainviewguy 4 · 0⤊ 0⤋
10qs 3 ds
10*.25=2.50+30=2.80
10*7=3
2006-12-01 05:19:07 · answer #8 · answered by Lizard 2 · 0⤊ 0⤋
10 .25
3 .10
2006-12-01 05:12:07 · answer #9 · answered by USMCstingray 7 · 0⤊ 0⤋