<human>:  Ali and Sara ate 80 small apples combined. Ali ate 4 times more apples than Sara. How many apples did Sara eat?
<bot>: Define a variable ** Let A be the number of apples Ali ate and S be the number of apples Sara ate.
Write an equation ** We have: A + S = 80 apples
Simplify ** And: A = <<4=4>>4S
Simplify ** Which means: 4S + S = 80
Simplify ** So: 5S = 80
How many apples did Sara eat? ** So the number of apples Sara ate is: S = 80 / 5= <<80/5=16>>16 apples
#### 16