Evaluate 7r - 15/s r=3 s=5 just to get yalls brain working

To complete your spring schedule, you must add calculus and physics. at 9: 30, there are three calculus sections and two physics sections; while at 11: 30, there are two calculus sections and three physics sections. how many ways can you complete your schedule if your only open periods are 9: 30 and 11: 30?

The water has been on the stove y=9.5x+62.1 after how many minutes will the tempature be 138.1 f

Which is the equation of a line perpendicular to the line with the equation 3x+4y=8