I only see part a, so for that one:
f(x) = 2x says that you’ll take your input (your x-value) and multiply it by 2 to get your output (your y-value).
f(7) = 2•7
f(9) = 2•9
f(-11) = 2•(-11)
f() = 2•
In part a, you’re asked for f(2), so this becomes :
f(2) = 2•2
= 4
