Sally has $21.40 in dimes and quarters in total is 100 coins. How many of each coin does she have ?
2007-05-20 11:07:27 · 12 answers · asked by Congi 1 in Science & Mathematics ➔ Mathematics
Just a a simple algebra problem:
Let x be the number of dimes and y the number of quarters.
0.10x+0.25y=21.4
x+y=100
solve through substitution:
x=100-y
0.10*(100-y)+.25y=21.4
10+.15y=21.4
.15y=11.4
y=76
x=24
24*.1+76*.25 = 21.4
tada!
2007-05-20 11:16:10 · answer #1 · answered by eight_ball8 3 · 0⤊ 0⤋
d = number of dimes
q = number of quarters
d+q=100 (the total number of coins is 100)
d = 100-q
.10d + .25q = 21.40 (the total value of the coins is $21.40)
.10(100 - q) + .25q = 21.40
10 - .10q + .25q = 21.40
10 + .15q = 21.40
.15q = 11.40
q=76 quarters
d=100-q
d=100-76
d=24 dimes
2007-05-20 11:15:25 · answer #2 · answered by lurhmann2 1 · 0⤊ 0⤋
The answer is 76 quarters and 24 dimes but I can't tell you how to solve it quickly. Maybe the answer will help you figure out the process.
2007-05-20 11:22:43 · answer #3 · answered by tatersaladofala 2 · 0⤊ 0⤋
Let q be the number of quarters she has and d be the number of dimes she has. So we get two equations:
.1d + .25q = 21.40
q + d = 100
now solve the system. d = 100 -q and substitue to get
.1(100 - q) + .25 q = 21.40
so 10 - .1q + .25q = 21.4
or .15q = 11.4
finally giving
q= 11.4/.15 = 76 so she has 24 dimes
2007-05-20 11:19:06 · answer #4 · answered by john_hart58 1 · 0⤊ 0⤋
x+y= 100
25x +10y =2140
Using substitution,
x+y= 100
y= 100-x
25x +10(100-x) =2140
25x +1000- 10x =2140
15x = 1140
x= 76 quarters
100-76= 24 dimes
2007-05-20 11:16:53 · answer #5 · answered by chess2226 3 · 0⤊ 0⤋
24 dimes and 76 quarters
2007-05-20 11:14:22 · answer #6 · answered by unknown 2 · 0⤊ 0⤋
76 Quarters & 24 Dimes
76Q = $19.00
24D = $2.40
_______________
100 Coins = $21.40
2007-05-20 11:20:44 · answer #7 · answered by CancerX79 2 · 0⤊ 0⤋
d=24; q=76
2007-05-20 11:15:58 · answer #8 · answered by Sugar High to Love High 2 · 0⤊ 0⤋
76 quartersx0.25=$19
14 dimesx0.10=$2.40
$19+$2.40=$21.40
76quarters and 24 dimes.
2007-05-20 11:29:40 · answer #9 · answered by Dilan F 1 · 0⤊ 0⤋
x = number of dimes
100-x = number of quarters
.1x +.25(100-x) = 21.4
.1x +25 -.25x =21.4
-.15x = -3.6
x = 24 = # of dimes
100-x = 76 = # of quarters
2007-05-20 11:15:20 · answer #10 · answered by ironduke8159 7 · 0⤊ 0⤋