The numbers next in the parenthesis next to the f are telling you to plug in those numbers for x in the equation. this leaves you with 3 different equations thus 3 different answers. this leaves us with f(1) = 3(1) + 7, f(3) = 3(3) + 7, and f(10) = 3(10) + 7. you then do the math in each problem which then leaves us with the answers f(1) = 10, f(3) = 16, and f(10) = 37. the f(x) can also be rewritten as y, both mean the same thing.