<human>:  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?
<bot>: How much did the t-shirt cost after the 50% discount? ** After the 50% discount, the t-shirt cost 20 * 0.5 = $<<20*0.5=10>>10.
How much money did they spend in total? ** So in all, the 4 friends spent 4 * $10 = $<<4*10=40>>40.
#### 40