Let x be how much student pays for one hour to use the telescope
Let y be how much student pays for one hour to use the supercomputer.
Equation for student 1:
Equation for student 2:
Use both equations above as a system of equations to solve x:
1. Solve y in the equation for student 1:
2. Substitute the y in the second equation by the value you get in step 1:
3. Solve x:
Then, A student pays $7.5 to use the telescope for one hour