Answer:
I am pretty sure it is the 3rd one
(In geometry, an isosceles triangle is a triangle that has two sides of equal length. And i think 3 of them are an isosceles triangle)
So i think here you would FOIL. so -5x^2+10x-5x+10 and then combine like terms :)
T=the amount of shirts
12t-20-8t=100
12t-8t=120
4t=120
t=30
So they must sell at least 30 shirts to make $100.
