Quilt
Step-by-step explanation:
The last terms must multiply to the last terms (confusing)
example
if ax^3+bx^2+c+d=(ex+f)(gx+h)(jx+k) then
d=fhk
so
70 is last term
we got 2 and 5
2*5*?=70
10*?=70
divide by 10
?=7
the missing number is 7
Plug
into the equation of the ellipsoid:

Complete the square:

Then the intersection is such that


which resembles the equation of a circle, and suggests a parameterization is polar-like coordinates. Let



(Attached is a plot of the two surfaces and the intersection; red for the positive root
, blue for the negative)
Each individual contributed $x
3x=$19.50
x=$6.50
Each friend contributed $6.50