Isaiah has $7.15 in Dimes and Nickels.He has a total of 91 coins.How many good each coin does he have?
x = nickel amount in nickles .05 x
91 -x = dimes amount in dimes .10 (91-x) these two amounts summed together = 7.15
.05 x + .10 (91-x) = 7.15
solve for 'x' the number of nickels then #dimes = 91-x