Question

Jack took 2 1/4 hours to complete a project. John took 3/8 hours longer to complete the same project. How long did John take to complete the project?

Answer 1

It takes Jack 2 1/4 hours (or 9/4 hours) to complete a project. John takes 3/8 hours longer.

We need to add 9/4 + 3/8

First, make the denominators equivalent.

We can do this by multiplying 2/2 to 7/2 which makes the denominator 8 (since 3/8 is already 8)

9/4 x 2/2 = 28/8
(note that we can do this because 2/2 is 1 and multiplying a number by 1 doesn't change its value)

Add 28/8 + 3/8
28/8 + 3/8 = 31/8

31/8 hours is our final answer, as a mixed number it is 3 7/8 hours :)