Solution:

I(1) + ate(2^3 is 8) + Some(Sum symbol) + Pie(Symbol)
= I Ate Some Pie and It Was Delicious

Solution:

Summary

Solution:

Open doors.

Solution:

Greenhouse.

Solution:

O + Pi + nion (Pi In Onion)
= Opinion

Solution:

MOB + I(pointing to me) + Le (Bruce Lee) = MOBILE.

Solution:

I Over Ate

Explanation:
Check the mathematical solution on the image below.
Also, 8 in 2018 resembles a fat person.

Solution:

Slumdog Millionare = Slum + Dog + Million + air

Solution:

12 Angry Men

Explanation:
12 (dozen = 12)
Angry (Angry Bed)
Men

Solution:

One Night Stand.

Explanation:
Number 'One' + Knight(chess piece) + st + and(symbol &)