x = adult tkts
y = student tkts
3x = value of adult tkts
1.5y = value of student tkts
x + y = 105
3x + 1.5y = 250
Do you need help solving those two equations for x and y?
Try tripling the first equation and then subtracting the second.
3x + 3y = 315
3x + 1.5y = 250
1.5 y = 65
y = 43 1/3
x = 105 -y = 61 2/3
There is something wrong with the data provided. x and y should be integers, but there are no integer solutions.