I think you have to divide
Each football is sold for $9.95. To make one of these football costs $7.10.
There is a profit of $2.85. Divide 11,400 by 2.85 to see how many footballs would have to sell to break even.
11,400 / 2.85 = 4000.
4000 footballs would have to be sold to break even.
Answer is 12.73
Use Pythagorean theory
Split square into two right triangles with diagonal line. To find the diagonal
a^2 + b^2 = c^2
9^2 + 9^2 = c^2
162= c^2
Take square root of both sides
12.73 = c