You eat 8 strawberries and your friend eats 12 strawberries from a bowl. There are 20 strawberries left. Which equation and solution give the original number of strawberries?

1: s+8=12+20;s=24

2: s+12=8+20;s=16

3: s−8−12=20;s=40

4: 20−s=8+12;s=0