You can put this solution on YOUR website! Since there are two unknown amounts (number of nickels and number of quarters), you should look for two equations.
Let n = number of nickels
and q = number of quarters
"Ron has 15 coins " and "The coins are nickels and quarters" implies
n + q = 15 (1)
" total value of $1.95." implies
5n + 25q = 195 (2) (in cents)
There are several approaches to solving these two equations. One is to rearrange (1) and then substitute into (2) to get one equation with one unknown (then later plug back in to get 2nd unknown).
(1) > q = 15-n (1')
Substitute 15-n for q in (2):
5n + 25(15-n) = 195
5n + 375 - 25n = 195 (distributed the 25)
-20n +375 = 195 (combined like-terms)
-20n = -180 (subtracted 375 from both sides)
n = -180/-20 = 9 (divided both sides by -20)
n=9 > (from (1')) > q = 15-9 = 6
Ans : Ron has 9 nickels and 6 quarters
Check 9+6 = 15 (ok, good on coin count)
9*5 + 6*25 = 45 + 150 = 195 = $1.95 (ok, good on dollar amount)
