Question 1099636

Alice has saved 5.00 in dimes, quarters, and half dollars. She finds that she has 30 coins altogether and there are four times as many quarters as there are half dollars. How many dimes does Alice have ?
<pre>Let number of dimes and half-dollars, be D, and H, respectively
Then number of quarters = 4H
We then get: D + H + 4H = 30_____D + 5H = 30 ------- eq (i)
Also, .1D + .5H + .25(4H) = 5
.1D + .5H + H = 5
.1D + 1.5H = 5
D + 15H = 50 --- Multiplying by 10 ------ eq (ii)
10H = 20 ------- Subtracting eq (i) from eq (ii)
H, or number of half-dollars = {{{highlight_green(matrix(1,3, 20/10, "=", 2))}}}
Number of quarters: {{{highlight_green(matrix(1,3, 4(2), "=", 8))}}}
Number of dimes: {{{highlight_green(matrix(1,5, 30 - 5(2), "=", 30 - 10, "=", 20))}}}