a)
Check the picture below.
b)
volume wise, we know the smaller pyramid is 1/8 th of the whole pyramid, so the volume of the whole pyramid must be 8/8 th.
Now, if we take off 1/8 th of the volume of whole pyramid, what the whole pyramid is left with is 7/8 th of its total volume, and that 7/8 th is the truncated part, because the 1/8 we chopped off from it, is the volume of the tiny pyramid atop.
Now, what's the ratio of the tiny pyramid to the truncated bottom?

The easier way is online games.
Answer:
326
Step-by-step explanation:
l x w
7x8
25x6
4x30
326
Add 16.937 and 7.5. It's basically doing the problem backwards.
The area of the sector which is the white triangle adding the shaded region is 68.9/360*π*9.28^2=51.78005(rounding to 5th digit after decimal point for accuracy before we do final round for answer)
The area of the white triangle in the sector has area 1/2*9.28^2*sin(68.9)= 40.17223(rounding to 5 digits again for some accuracy.
Now we take out the white triangle from the sector.
51.78005-40.17223=11.60782
rounding to the nearest tenth we get 11.6 cm^2
Problem done!
Hope this helped and if you have any questions about my explanation just ask in the comment and I will answer.