4. in cell i4, enter a formula that uses the if function and structured references to calculate customer sales growth (as a %).
a. growth can be calculated if the value in the 2015 purchases column is greater than 0.
b. to calculate growth (as a %), divide the value in the growth ($) column by the value in the 2016 purchases column.
c. if the value in the 2015 purchases column is not greater than 0, return a value of n/a. if necessary, copy the formula you created in cell i4 to the range i5: i27.