Brian is a software salesman. Let y represent his total pay (in dollars). Let x represent the number of copies of Math is Fun he sells. Suppose that x and y are related by the equation 1600+70x=y . Answer the questions below. Note that a change can be an increase or a decrease. For an increase, use a positive number. For a decrease, use a negative number.

What is the change in Brian's total pay for each copy of Math is Fun he sells? $____

What is Brian's total pay if he doesn't sell any copies of Math is Fun? $___