a)

96 - 32 = 64

When he has 342 marbles left, each cousin already has 32 marbles.

Now if he wants each of them to have a total of 96 marbles instead, he has to give each cousin 64 more marbles.

But his 342 marbles is not enough. He is short of 170 marbles.

Number of marbles he needs such that each cousin gets 64 more

= 342 + 170
= 512

Number of cousins he has
= 512 ÷ 64
= 8


b)

When he has 342 marbles left, his cousins have a total of 32 x 8 = 256 marbles

So his total number of marbles
= 256 + 342
= 598



Or


If he had no shortage of marbles,

Total number of marbles his cousins got altogether

= 96 x 8
= 768

But since we know he had a shortage of 170,

Number of marbles he actually had
= 768 - 170
= 598

Thanks!