In order to find f(-2) when f(x)=5x+3, you the first thing you must do is to set up your equation which should look like this:
f(-2)=5(-2)+3
When f(-2), it is stating in mathematical terms that the x value is -2, therefore you would substitute the x value with -2. When you simplify the expression, you should get -10+3 which results in your answer, -7.
