Given the function f(x) = x – 1, then what is f(-x) as a simplified polynomial?

The function a represents the cost of manufacturing product a, in hundreds of dollars, and the function b represents the cost of manufacturing product b, in hundreds of dollars. a(t) = 5t + 2 b(t) = 7t - 2t +4 find the expression that describes the total cost of manufacturing both products, a(t) + b(t). a. 7t^2 - 7t + 2 b. 7t^2 + 3 +6 c. 7t^2 + 7t - 6 d. 7t^2 - 3t + 6

I'm confused on this could anyone me and show me what i need to do to solve it.

Iknow its nothing to do with education, but what type of thing should i wrote here? ? : ) its for mcdonald's btw.