-5+x-7 what does x equal

Since there is no equal sign x can not have an actual value, the equation simplified would be

x-12

Step-by-step explanation:

The way to solve this is to combine like terms

-5 + ( -7 ) = -12

If you have any questions feel free to ask - Mark

(f - g)(x) = 5x^3 - 3

step-by-step explanation:

rearrange these functions vertically, with like terms in separate columns:

f(x) = 5x^3 - 2

g(x) =         +1

now subtract, column by column:

(f - g)(x) = 5x^3 - 3