Answer B is the correct choice. To determine this answer, one must look at the number in the parentheses in each expression. In the expression for company A, it is 0.70. This actually represents a decrease, as it is a number less than 1 (exactly 1 would be 100%/no change). You may also determine this by setting up the equation: 1 + p = 0.70, where p indicates the percent increase or decrease. When 1 is subtracted from from both sides, the result is p = -0.30, or 30%, with the negative indicating the decrease.
The equation for company B has 1.90 in parentheses; the number is more than one, indicating an increase. The same equation can be applied to prove this: 1 + p = 1.90. Subtract one from both sides and the result is p = 0.90, or 90%, and being positive, represents an increase.
The number outside of the parentheses in each equation represents the starting point of the sales and does not affect the rate of increase.
The x in each equation represents a time factor that can be used to calculate the sales at a certain point of time. However, the problem gives no indication about any time period involved, thus it is irrelevant to the question being asked about percent of increase.