Mark give 20% of his marbles to john and three eighths of the remainder to harry. if he had 40 remain, how many marbles he had a first?

Answer 1

0.2 m to mark, 0.9 m left
3/8 of 0.8 m to Harry, 5/8 of 0.8 m left
so
5/8 * 8/10 * m = 40
1/2 * m = 40
m = 2 * 40

Answer 2

typo, 0.8 left not 0.9

Answer 3

Mark has X marbles.
x-0.2x = 0.8x remains.

0.8x-3/8*0.8x = 0.8x-0.3x = 0.5x remainder.
0.5x = 40.
X =

Answer 4

so that means x equals 40 divided by 0.5 and that would be the answer.