There's two ways to do this problem: y=mx+b and normal division. To divide, just do 390 ÷ 40 and 234 ÷ 24. Both equations should equal 9.75. The other way is a bit more complicated, but it's the way I solved it. They give you two points, (24,234) and (40,390). 10 is b, now to find the slope. To find the slope you do y2-y1 over x2-x1. Plug the numbers in: 390-234 over 40-24. Simplify: 156/6, which equals 9.75. So, y=9.75x+10. The answer is: after 10 hours of work, she'll make $9.75
I hope that helped!