Answer:
y = 150x^2 -60x +6
Step-by-step explanation:
Do what the problem statement tells you: substitute for u.
y = 6u^2
y = 6(5x -1)^2 . . . . . . . . . . substitute 5x-1 for u
y = 6(25x^2 -10x +1) . . . . expand the square
y = 150x^2 -60x +6 . . . use the distributive property
