Ok for this problem, there are 2 equations representing hall A and hall B
hall A: y=76x+862 where x=number of dinners and y=total cost
hall B: y=75x+894 for the same variables
To find where the 2 meet, simply substitute one equation into the other, creating: 76x+862=75x+894
Solving this, we find that x=32, so at 32 guests, the cost would be the same
For part 2, put the answer for part 1 into either equation from the start, so y=76(32)+862, or y=3294
And we already found that x=32, which represents the # of guests