Question 255123
I would not use x for how many of each kind.
I would use a for number of adult tickets
and s for student tickets
What they really want is how many adult and how many student tickets since we know the total is 788.
a+s=788
s=788-a
2.50a+1.25s=1400
you can substitute 788-a for s
2.50a+1.25(788-a)=1400
Now we have one unknown in one equation