Find the slope using the formula [ y2-y1/x2-x1 ].
-9-(-12)/-15-(-24)
3/9
1/3
Find the y-intercept using the formula [ y = mx + b ].
y = 1/3x + b
-12 = 1/3(-24) + b
-12 = -8 + b
-4 = b
Use (18, 2) to see if the line passes through it
y = 1/3x - 4
2 = 1/3(18) - 4
2 = 6 - 4
2 = 2 TRUE
Thus, the line does pass through (18, 2).
Best of Luck!