Answer:
[tex]60+27t+3t^2[/tex]
Step-by-step explanation:
Let's put 5+t wherever we have x in the original: rest is simple algebra.
[tex]w(5+t) = 3(5+t)^2 -3(5+t) = 3(25+10t+t^2)-15-3t =75+30t+3t^2-15-3t =60+27t+3t^2[/tex]
