He spent $50.00 and 80% of the meal went to entrees so he spent 50*.80 = $40.00 on entrees
He spent $50.00 and $40.00 went to entrees so that leaves $50 - $40 = $<<50-40=10.00>>10.00 for appetizers
Each appetizer costs the same amount and he spent $10.00 all together so each appetizer is $10/2 = $<<10/2=5.00>>5.00
#### 5