The number of marbles in Amin’s collection is 80% of the number in Rahim’s collection. If Rahim has 80 more marbles than Amin, how many marbles do they have altogether?

A 720

B 120

C 135

D 400

Correct Answer: Option A

If Rahim's Collection is X

Then, Amin's Collection is 0.8X

Now, A/Q,

X - 0.8X = 80

or, 0.2X = 80

or, X = 80/0.2 = 400

So, Rahim has 400 marbles

and Amin has 0.8*400 = 320 marbles

Together they have = 400+320 = 720 marbles