Let,
x = Maps sold
y = Profit
a.) Since the graph shows it's linear, let's create an equation applying this formula,
![\text{ y = mx + b}](https://img.qammunity.org/2023/formulas/mathematics/college/jktsxg4fkjzyla0fu188v2p7nlvte8hjri.png)
From the graph, let's use the ordered pairs (40, 0) and (0, -200) from the given data,
Let's solve for m,
![m\text{ = }\frac{0\text{ - (-200)}}{40\text{ - 0}}\text{ = }(200)/(40)\text{ = 5}](https://img.qammunity.org/2023/formulas/mathematics/college/n5b3fgb3dbd3qyh29l64vwajt8urn1vlsh.png)
Let's solve for b, let's use (40,0) for x and y.
![\text{ y = mx + b}](https://img.qammunity.org/2023/formulas/mathematics/college/jktsxg4fkjzyla0fu188v2p7nlvte8hjri.png)
![0\text{ = (5)(40) + b}](https://img.qammunity.org/2023/formulas/mathematics/college/ye2qp00oxxccoxlv6neiiatgun855czq7v.png)
![\text{ b = -200}](https://img.qammunity.org/2023/formulas/mathematics/college/um3kizd8xf5srge8fw81z0n4mooejg7lqy.png)
Thus, the equation will be,
![\text{ y = 5x - 200}](https://img.qammunity.org/2023/formulas/mathematics/college/rcl138hxmis7d3760toh1c22azx8001ijf.png)
Or we can rephrase it as an equation to solve for the profit,
![\text{Profit = 5(Maps sold) - 200}](https://img.qammunity.org/2023/formulas/mathematics/college/kihlfg0um33unnjf1dvte9zhxarxurvr7q.png)
b.) The ordered pairs (40, 0) and (0, -200) represents Brian's profits from selling a different number of maps.
(40, 0) = Brian will get no profits if he'll only sell 40 maps. His sale will only be just breakeven to his initial expenses.
(0, -200) = Brian will lose $200 which is his initial expense if he couldn't sell a map.
c.) Brian's profit if he sells 300 maps.
Let's use the formula we made from Part. a,
![\text{ y = 5x - 200}](https://img.qammunity.org/2023/formulas/mathematics/college/rcl138hxmis7d3760toh1c22azx8001ijf.png)
x = 300, we get,
![\text{ y = 5(300) - 200 = 1500 - 200 = 1300 = \$1,300}](https://img.qammunity.org/2023/formulas/mathematics/college/lizvgmalls89xi5hvj6wtori1ggwyq9o2n.png)
Brian will earn $1,300 dollars if he sells 300 maps.