Answer:
120 minutes
Step-by-step explanation:
large horse + small horse = together
1 pool/40 minutes + x = 1pool/30 minutes
1/40 + x = 1/30
subtract 1/40 from both sides
x = 1/30 - 1/40
use 120 as common denominator
x = 4/120 - 3/120
x = 1/120
x = 1 pool / 120 minutes
It takes the small horse 120 minutes
