Answer:
![20\ lawns = \$240](https://img.qammunity.org/2021/formulas/mathematics/college/i5fhhllnvi8zez6icbwfzfgj4ir4icidpu.png)
![9 \ lawns = \$108](https://img.qammunity.org/2021/formulas/mathematics/college/xvn7fj4w4lkyrzbgg97b7j5j18ztdo71ex.png)
See Attachment for Graph
Explanation:
Given
![1\ lawn = \$12](https://img.qammunity.org/2021/formulas/mathematics/college/4dh3gmj4jmie2t8ctdg65x0t100kd4vqy8.png)
Solving (a): Number of lawns in $240
![1\ lawn = \$12](https://img.qammunity.org/2021/formulas/mathematics/college/4dh3gmj4jmie2t8ctdg65x0t100kd4vqy8.png)
Multiply both sides by 20
![20 * 1\ lawn = \$12 * 20](https://img.qammunity.org/2021/formulas/mathematics/college/2e8au2hjaxfu9ce80cdvqv4z8yhtss8v6h.png)
![20\ lawns = \$240](https://img.qammunity.org/2021/formulas/mathematics/college/i5fhhllnvi8zez6icbwfzfgj4ir4icidpu.png)
Solving (b): Cost of mowing 9 lawns
![1\ lawn = \$12](https://img.qammunity.org/2021/formulas/mathematics/college/4dh3gmj4jmie2t8ctdg65x0t100kd4vqy8.png)
Multiply both sides by 9
![9 * 1\ lawn = \$12 * 9](https://img.qammunity.org/2021/formulas/mathematics/college/wcg6jc0l6my5rw0buwnpqnatg68mdotrix.png)
![9 \ lawns = \$108](https://img.qammunity.org/2021/formulas/mathematics/college/xvn7fj4w4lkyrzbgg97b7j5j18ztdo71ex.png)
To create a graph, we need to generate a formula;
If
![1\ lawn = \$12](https://img.qammunity.org/2021/formulas/mathematics/college/4dh3gmj4jmie2t8ctdg65x0t100kd4vqy8.png)
![2\ lawn = \$24](https://img.qammunity.org/2021/formulas/mathematics/college/xnch20z0wratzx0wmlrlxjdri43zm8lmv8.png)
![3\ lawns = \$36](https://img.qammunity.org/2021/formulas/mathematics/college/esx1zl014ji8o7tctopt670x9utq4my6q5.png)
![x\ lawns = \$12x](https://img.qammunity.org/2021/formulas/mathematics/college/ime4e0yiy6olzd20pxp13qogeys9du4fhm.png)
So:
The graph formula is
![y = 12x](https://img.qammunity.org/2021/formulas/mathematics/high-school/qi18ptowfkrcs1hf4qalqhtqj4wci8s2nv.png)
See Attachment for Graph