I think the answer is x times 2 - 61
Hope this helps! Is from the app Photomath.
The area formula of a triangle is 1/2 ×base ×height
so 1/2×3 in ×8 in ---> 1/2×24 in = 12 in
3 are left.
3/7 means there were 7 slices, but it's missing 4 slices. (Eaten)
i hope this helps :)