Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
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?

### Response:
The first 4 customers bought 4 paintings each, so 4 customers * 2 paintings each = <<4*2=8>>8 paintings.
The next 12 customers bought 1 painting each, so 12 customers * 1 painting each = <<12*1=12>>12 paintings
The last 4 customers bought 4 paintings each, so 4 customers * 4 paintings each = <<4*4=16>>16 paintings.
There were 20 customers total, so 20 customers - 4 customers - 12 customers - 4 customers = 0 customers.
Since there is 0 customers left, that means Tracy sold 8 paintings + 12 paintings + 16 paintings = <<8+12+16=36>>36 paintings total.
#### 36