Question

Which one?Please help its extra credit!

Answer 1

12 weeks

Explanation:

if 280=420

then 8=×

cross multiply

280×=420×8

280×=3360

divide both sides with the co efficient of x

280×/280=3360/280

leaving the answer to be 12

Answer 2

So he deposits a certain amount each week
So he deposited this amount 8 times and got 280 dollars
So clearly he deposits ($280/8) each week
Now he needs 420 dollars
Decide this by the amount deposited each week to get the no of weeks
420 / (280/8) => 12 weeks