Height of the water after 3 minutes is 31.25 inches
Solution:
Given that height of the water in a fish pond is 42.5 inches
Water is being drained from the pond at a rate of 3.75 inches per minute
To find: height of the water after 3 minutes
According to given information,
Water drained in 1 minute = 3.75 inches
So height of the water after 3 minutes is calculated by following steps:
1) find how much water is drained in 3 minutes
2) subtract value obtained in step 1 from total height of water in fish pond
Step 1:
water is drained in 3 minutes = Water drained in 1 minute x 3

Thus water drained in 3 minutes is 11.25 inches
Step 2:
height of the water after 3 minutes = total height of water in fish pond - water drained in 3 minutes
height of the water after 3 minutes = 42.5 - 11.25 = 31.25 inches
Thus height of the water after 3 minutes is 31.25 inches