Step-by-step explanation:
All these fancy terms is confusing. We just need to substitute the original equations into the final problem statement.
[tex]p(x) = 10x - (8x+40) = 10x - 8x - 40[/tex]
We can then substitute 100 for x and solve.
[tex]p(100) = 10(100) - 8(100) - 40[/tex]