To Find: The values of a and b when the line = 1 passes through the points (8, -9) and (12, -15).

Given : the equation of the line : = 1 equation 1

Also (8, -9) passes through equation 1

= 1

8b - 9a = ab equation 2

And (12, -15) passes through equation 1

= 1

12b - 15a = ab equation 3

Solving equation 2 and 3

a= 2.

Put a=2 in equation 2

8b- 9a = ab

8b -18 = 2b

6b =18 b=3

Hence the values of a and b are 2 and 3 respectively.