p = pennies
q= quarters
p = 2q+5 (1)
.25q+.01p=1.67 (2)
substitute the equation for pennies (1) into the 2nd equation
.25q+.01(2q+5)=1.67
distribute
.25q +.02q +.05 = 1.67
combine like terms
.27q +.05 =1.67
subtract .05 from each side
.27q = 1.62
divide by .27
q=6
p=2q+5
p=2(6)+5
p=12+5
p=17
There are 6 quarters and 17 pennies