Answer:
3x-12=78
Explanation:
This is my thinking:
So because x is the cost of the weekend admission, the problem says 12 less than 3 times the cost of the weekend admission. The 3 times the cost of the weekend admission is the 3x, and the problem says 12 less than and that is the -12. And the whole equation is being taken from 78, so
3x-12=78.