Question

Jennifer uses the formula P = 0.5e - 5 to determine the profit (P) she makes from selling any number of erasers (e). Last week Jennifer had a profit of $63. How many erasers did Jennifer sell?

Answer 1

To solve this you must work backward. First, plug in all of the information you know into the equation.
63=0.5e-5
Now you must solve the equation
0.5e=63+5
0.5e=68
To find e, the last step is to multiply
e=68*2
e=136
She sold 136 erasers

Answer 2

You would have to set the equation to the profit Jennifer got, which you know to be 63 dollars:
63=0.5e-5
To begin solving for e, which represents the number of erasers sold, add five to each side to get e alone.
68=0.5e
Multiply each side by two to get a whole x value on the right side
136=e
Jennifer sold 136 erasers