We can answer the problem using a rule of three, simple, direct proportion and also using fractions. First the rule of three: 8 apples ------> 15 min 16 apples ----> x
x = (16)(15)/8 x = 30 therefore he can eat 16 apples in 39 minutes.
We can also equate fractions like so: 8/15 = 16/y and solve for y: y = 15*16/8 y = 30 the same answer