Answer :
So , at first we should calculate the power because in calculating order we have:
first power or radical
then multiply or division
then + or -
so according to the rules we must do:
1)(x-3)^2=x^2 -6x +9
2)5(x^2 -6x +9)=5x^2 -30x +45
3)then -6 and we have:
Y=5x^2 -30x +39