Answer:
See below for explanation of the examples.
Step-by-step explanation:
Left example
It is an exercise in addition, i.e. 48+122=170, the answer is written in the bottom box.
Right example
It is an exercise in subtraction, i.e. 8 1/2 - 3 1/2 = 5
The answer is written in the bottom box.
There is no indication though as to when to do the addition, and when to do the subtraction. Perhaps it would be shown in the rest of the page (not shown).
I guess you are asking what is the shape of the cross section.
It will be an ellipse.
