I’m trying to help my brother with his homework but we both can’t solve this one

Well there are 2 pecks in 1 kenning
So that's 2 × 1 peck = 1 kenning

2 kennings in 1 bushel
That's 2 × 1 kenning =  1 bushel

2 bushels in 1 strike
That's 2 × 1 bushel =  1 strike

4 strikes in 1 quarter
That's 4 × 1 strike =  1 quarter

4 quarters in 1 chaldron
That's 4 × 1 quarter =  1 chaldron

So now substitute again and again:

4 × 1 quarter =  1 chaldron

4 × ( 4 × 1 strikers ) =  1 chaldron

4 × ( 4 × ( 2 × 1 bushel ) ) =  1 chaldron

4 × ( 4 × ( 2 ×  ( 2 × 1 kenning ) ) ) =  1 chaldron

4 × ( 4 × ( 2 ×  ( 2 × ( 2 × 1 peck ) ) ) ) =  1 chaldron

4×4×2×2×2 peck = 1 chaldron

128 peck = 1 chaldron

So that's 128 × 1 peck = 1 chaldron.

Hope this helps.