Answer:
![y = (1)/(3)x-2](https://img.qammunity.org/2022/formulas/mathematics/college/h7xmaffjvh3o6k18ourujwtsd903aybcm5.png)
This is the same as writing y = (1/3)x - 2
Slope = 1/3
y intercept = -2
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Step-by-step explanation:
We first need to determine the slope
![m = (y_2-y_1)/(x_2-x_1)\\\\m = (-3-3)/(-3-15)\\\\m = (-6)/(-18)\\\\m = (1)/(3)\\\\](https://img.qammunity.org/2022/formulas/mathematics/college/px2wy6k7suhyxyzhc75kpemw09kgzzio1v.png)
Then we'll use this value of m, along with (x,y) = (15,3), to determine the y intercept b value.
![y = mx+b\\\\3 = (1/3)(15)+b\\\\3 = 5+b\\\\3 - 5 = b\\\\-2 = b\\\\b = -2](https://img.qammunity.org/2022/formulas/mathematics/college/bob1clu5gyb0x8ai0i6etjm8642iu5f1jc.png)
You could use the other point (-3,-3) as well
![y = mx+b\\\\-3 = (1/3)(-3)+b\\\\-3 = -1+b\\\\-3 +1 = b\\\\-2 = b\\\\b = -2](https://img.qammunity.org/2022/formulas/mathematics/college/v1o256nhvppqsvp06ipsputck4r9ce0tq5.png)
Either way, we end up with the same y intercept. You don't need to show both sets of steps when computing b. You only need to pick one set of steps.
Since m = 1/3 and b = -2, we go from y = mx+b to y = (1/3)x - 2 which is the same as writing
![y = (1)/(3)x-2](https://img.qammunity.org/2022/formulas/mathematics/college/h7xmaffjvh3o6k18ourujwtsd903aybcm5.png)