Archy bought 15 gallons of gas for $23.85. joe bought 16 gallons of gas for $24.48. who paid less per gallon?

Archy:  15 gallons ... $23.85
               1 gallon ...$ x = ?

x * 15 = 1 * 23.85    /15
x = 23.85 / 15
x = $1.59 per gallon

Joe:  16 gallons ... $24.48
           1 gallon ... $ y = ?

y * 16 = 1 * 24.48    /16
y = 24.48 / 16
y = $1.53 per gallon

Result: Joe paid less per gallon.

The answer to that is 6