One fifth of a thing is more than one eighth 120, so this 120 corresponds to this thing's (1/5- 1/8)=3/40, and the whole thing is120/(3/40.

second

Ibid., the cut of 42 corresponds to (1-40%)=60%.

So the total amount =42/60%=70

That leaves 28.

Cut 3/7, so cut =28*3/7= 12.