<human>:  Tracy set up a booth at an art fair. 20 people came to look at her art. Four of those customers bought two paintings each. The next 12 of those customers bought one painting each. The last 4 customers bought four paintings each. How many paintings did Tracy sell at the art fair?
<bot>: How many paintings did the first 4 customers buy? ** The first 4 customers bought 4*2=<<4*2=8>>8 paintings
How many paintings did the next 12 customers buy? ** The next 12 customers bought 12*1=<<12*1=12>>12 paintings
How many paintings did the last 4 customers buy? ** The last 4 customers bought 4*4=<<4*4=16>>16 paintings
How many paintings did Tracy sell at the art fair? ** In total Tracy sold 8+12+16=<<8+12+16=36>>36 paintings
#### 36