Evaluate the expression 81 minus 8 to the second power. 81 minus 8 to the second power

Danielle earns a 7.25% commission on everything she sells at the electronics store where she works. she also earns a base salary of $750 per week. what were her sales last week if her total earnings for the week were $1,076.25?

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)

Use the quadratic function to predict f(x) if x equals 8. f(x) = 25x2 − 28x + 585