help please!

$f(2) = 5(2^2) - \dfrac 1 2 + 3 = \dfrac{45}{2}\\ g(2) = 2^2 - k = 4-k\\ f(2)-g(2)=2\\ \dfrac{45}{2}-(4-k) = 2\\ \dfrac{37}{2} + k = 2\\ k = -\dfrac{33}{2}$

thanks rom!