You are measuring a board so you can cut it. You need to cut the wood from 1 1/4 inches to 1/2 inch. How long is the piece of wood you are going to cut?
To determine the length of the wood you need to cut, you need to find the difference between the original measurement of 1 1/4 inches and the final measurement of 1/2 inch.
To do this, subtract the final measurement from the original measurement:
1 1/4 inches - 1/2 inch
To subtract fractions, you need a common denominator. In this case, the common denominator is 4.
Convert 1 1/4 to a fraction with a denominator of 4:
1 1/4 = (4/4) + 1/4 = 5/4
Now you can subtract the fractions:
5/4 - 1/2
To subtract fractions, the denominators must be the same, so multiply the numerator and denominator of 1/2 by 2:
5/4 - (1/2) * (2/2) = 5/4 - 2/4 = 3/4
The length of the piece of wood you are going to cut is 3/4 inch.