Hello, could you please explain this to me?

Find the value of r(q(4)), so first you need to find the value of q(4).

q(4), this means that x = 4, so substitute/plug it into the equation to find the value of q(x) when x = 4:

q(x) = -2x - 1      Plug in 4 into "x" since x = 4

q(4) = -2(4) - 1

q(4) = -8 - 1

q(4) = -9        

Now that you know the value of q(4), you can find the value of r(x) when x = q(4)

r(x) = 2x² + 1

r(q(4)) = 2(q(4))² + 1      Plug in -9 into "q(4)" since q(4) = -9

r(q(4)) = 2(-9)² + 1

r(q(4)) = 2(81) + 1

r(q(4)) = 163           163 is the value of r(q(4))