See the attached picture.
The negative sign in front of the 2 makes the graph an upside down U shape.
3x+4=10
Subtract 4 from both sides
3x=6
Divide both sides by 3
X=2
Sides = 10,10,5
Problem 5. 4x+1=29
Subtract 1 from both sides
4x=28
X=7
I believe that the answer would be 2 but im not 100% positive
A = pi * r * r
A = 3.14 * 10000 * 10000 = 314000000 ft^2