From a board 4 feet 2 inches long, a board 3 feet 7 inches long is cut what is the lengh of the remaining board?

Math:

Well, you know that 12 inches goes into 1 foot.

So, let's start with just making everything into inches.

4 feet * 12 = 48+2 = 50 inches.

3*12 = 36 inches + 7 = 43 inches.

50 - 43 = 7.

Your answer:

7 inches.