t[sx)] can be evaluated by replacing x with s(x) in the equation for t(x).

t[s(x)] = 2[s(x)]^{2} + 2

= 2(-x-1)^{2} + 2 {Replacing s(x) with -x -1}

So

t[s(3)] = 2(-3-1)^{2} + 2 {Substitute 3 for x}

= 2(-4)^{2} + 2

= 34

Or

s(3) = -3 -1 = -4

t[s(3)] = 2[-4]^{2} + 2

= 34