can you solve the maths below

Question

The average weight of a crew of 8 in a boat is 80kg. When a new man replaces one of them who weighs 76kg.the new weight increases to 81.5kg.how much does the new man weigh?

Answer 1

(8)(80) = 640  original weight of all

640 - 76 = 564 weight after man leaves

(8)(81.5) = 652 weight after new man enter

 

652 - 564 = 88