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!
The 31st term of this sequence is 189.
9, 15, 21, 27, 33 (5), 39, 45, 51, 57, 63 (10), 69, 75, 81, 87, 93 (15), 99, 105, 111, 117, 123 (20), 129, 135, 141, 147, 153 (25), 159, 165, 171, 177, 183 (30), 189.
You didn't share the price list of the items... but together they have $12.00