What is the product of five and a number, decreased by eleven

Acompany is making new soccer uniforms for a team. the company uses 2.5 yards of fabric for each shirt. the company uses 82.5 yards of fabric to make shirts and shorts for 15 players. the equation and solution below represents the situation. 15(2.5+x)=82.5; x=3 what does the solution, x=3, represent?

Me with this one question, and i'll upvote the brainliest answer

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)