Question

martin has a 4-inch board that he wants to be 3 11/16 inches wide. how much does he need to trim off?

Answer 1

You can set this up by subtracting 3 11/16 from 4.

convert 3 11/16 to improper fraction form by multiplying 3 times 16 and then adding it to 11 to get

59/16

make 4 in improper fraction 4/1. Next you need to find a common denominator which in this case will be 16.  Second fraction does not need to be changed because it already has our common denominator. For the first, multiply both top and bottom by the common denominator

4*16/1*16 - 59/16

64/16 - 59/16

Then do simple fraction subtraction.

5/16 of an inch needs to cut off of the 4 inch board to leave 3 11/16