The answer is amortization
1 quarter = 25 cents.
1 dime = 10 cents.
3 quarters = 3*25 = 75 cents.
10 cents = 1 dime.
75 cents = 75 / 10 dimes
= 7.5 dimes.
Therefore 3 quarters equal 7.5 dimes.
Y = 1.25x + 30 <== ur function
for 3 hrs.....x = 3
y = 1.25(3) + 30
y = 3.75 + 30
y = 33.75 <=== for 3 hrs