3 + 5 = 8
8 - 5 = 3
3 - 3 = 0
Answer:

Step-by-step explanation:
Hey there! I'm happy to help!
We want to see how many times bigger 2/5 is than 9/10. Let's call how much bigger 2/5 is b and solve below.
9/10b=2/5 (2/5 is b times larger than 9/10)
We divide both sides by 9/10, so your division would be 2/5÷9/10.
b=4/9
Therefore, the builder worked 4/9 times as long in the morning as he did in the afternoon.
Have a wonderful day! :D