Cody is paid on a graduated commission scale. For the first $10,000 of sales his commission is 3.50%. On the next $30,000 he
receives 5.50% commission and 8.50% for all sales after that.
What were Cody's sales in a month when he is paid $4,0407 For full marks your answer(s) should be rounded to the nearest
cent
Sales = $ 0.00

Let's use substitution. 
Since y = 4x - 1 in the second one we'll start with that.
Step 1: y = 8x − 9
Step 2: 4x - 1 = 8x − 9
Step 3: 4x = 8x − 8
Step 4: 8 = 4x
Step 5: 2 = x

Next we substitute x into one of the equations to find y
Step 1: y = 8x -9
Step 2: y = 8(2) - 9
Step 3: y = 16 -9
Step 4: y = 7

Hope this helps