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

### Instruction:
4 friends went to buy from a clothes shop. Every item was 50% off.  All four friends decided to buy a t-shirt. The original price of the t-shirt was 20 dollars. How much money did they spend in total?

### Response:
After the 50% discount, the t-shirt cost $20 * 0.50 = $<<20*0.5=10>>10.
So in all, the 4 friends spent $10 * 4 = $<<10*4=40>>40.
#### 40