65.7x- 3x(x+ 1)

66.-4(y+ 2) - 6y

67.3t(t- 5) + 6t squared

68.-x cubed+ 2x(x-x squared)

Exponents can be expressed like this

t squared = t^2

x cubed = x^3

Just one piece at a time.

7x- 3x(x+ 1) = 7x - 3x^2 - 3x = 7x - 3x - 3x^2 = 4x - 3x^2

-4(y+ 2) - 6y = -4y - 8 - 6y = -8 - 4y - 6y = -8 - 10y

You show us the next one.