Heller company manufactures lawn mowers and related lawn equipment. the managers believe the quantity of lawn mowers sold depends on the price of the mower and the price of a competitor’s mower. the table contains data on heller’s price, the competitor’s price and the number of units sold. use the data to estimate a multiple linear regression model, with the number of units sold as the dependent variable and the two prices as the independent variables.
based on your model, if heller’s price increased by $1 while the competitor’s price remained the same, how much do you estimate that the number of units sold would change? (if the number of units goes down, answer with a negative number; otherwise answer with a positive number.) report your answer as an integer.

competitor's price heller's price quantity sold
120 100 102,000
140 110 100,000
190 90 120,000
130 150 77,000
155 210 46,000
175 150 93,000
125 250 26,000
145 270 69,000
180 300 65,000
150 250 85,000