Question 22809
If P(x) = 4x^2+2x-7
and
R(x)= 2x^2+5x-3
and you are asked
R(x)-P(x)
then put your R = and your P = into the problem and solve.

(2x^2+5x-3) - (4x^2+2x-7)

-2x^2+3x+4

This can be carried on to solve and get answer to x but you didn't ask for that.  If you need to you can factor using foil or the quadratic formula.