59.70 for 6 hours of mowing and 1 hour of babysitting !
Start by looking at the vertex form of a quadratic function, f(x) = a(x - h)^2 + k. The variables h and k are the values of the vertex. Plug those in to get f(x) = a(x - 4)^2 + 5. To find the variable a, plug in the point given for the x and y values. So, you get (21) = a((8) - 4)^2 + 5. Solve for a algebraically, and you get a = 1. Finally, plug everything in and simplify the equation. You should get that the quadratic function is f(x) = x^2 - 8x + 21. Hope this helps!
100 cm = 1 meter
80 cm = 0.8 meter
200 meters/.8 meters = number of boards
250
You would subtract how many times Dion tagged bill with how many times bill tagged Dion, so 12 - 7 = 5