What is the missing step in this proof?

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?

9. (y^-5)^10y^10 a. y^-60 b. y^60 c. y^-150 d. y^150 find the simplified form of each expression. 10. (4/7^5)^2 a.8/14^10 b.16/49^25 c.16/49y^10 d.8/14y^25 11. determine if the number 3.43 times 10^-6 is written in scientific notation. if not, explain. a. yes; the number is written scientific notation. b. no; the first factor is not a number between 1 and 10. c. no; it is not written as a number times a power of 10

What is the 12th term of b(n)=-4-2(n-1)