Please help me , step by step explanation needed

Explanation

Part (a)

The smaller pyramid up top is the result of slicing at the halfway point.

This leads to the ratio 1:2 when comparing small side to larger side.

Cube both parts of that ratio to end up with 1:8 as the volume ratio.

This means if the smaller pyramid was say 1 cubic foot in volume, then the larger pyramid has a volume of 8 cubic feet.

Part (b)

Consider the case that,

The volume of the truncated base is 8-1 = 7 cubic feet.

The ratio of the smaller pyramid to the truncated base is 1:7

yes.. it's proven to be 36.

the answer for the question that you are asking is 4