Evaluate functions
w(n)=n^2-3n; find w(6)
h(n)=2n; find h(5)
h(x)=x^2+4x; find h(-7)
w(n)=n^2-3n; find w(6)
h(n)=2n; find h(5)
h(x)=x^2+4x; find h(-7)