The total amount in all four boxes is 80
Explanation:
We know that box A has 4 marbles, and it has 5% of the marbles in total. So we can set up a proportion.
4 1% 5%
--- = --- = ---
n 20% 100%
We want to figure out what n is. To do that, we first simplify 5/100 to 1/20. To get from 4 to 1, its divided by 4. We want to do the same thing to n (divide n by 4). To do this, we do the inverse operation of division, and we multiply 20 x 4, which is 80. Therefore, the total amount of marbles is 80.
