Hello there!
To start, use your slope-intercept equation y=mx+b where m is the slope.
Because the slope is 6 and you have a set of points already given, (1,30), you can plug this into the equation to solve for b to get your equation:
30=6(1)+b
30=6+b
b=24
Now that you have the slope of 6 and the y-intercept of 24, you now have your equation as y=6x+24
Because you have this equation, you can now plug in your given x values from the table to solve for the y values or the variables a and b.
To solve for a, plug in your x-value:
y=6(0)+24
y=24
When you solve, you get y=24 which means the value of a is 24.
Now plug the x-value of 2 into the equation to solve for b:
y=6(2)+24
y=36
When you solve, you get y=36 which means b is 36.
Now that you have that a=24 and b=36, you can use this information to solve for question a and question b.
a.) Since the the question asks for b-a, plug in your values:
36-24
When you subtract b and a, you should get your answer as 12.
b.) Since the question now asks for ab, plug in your values:
(24)(36)
Then, when you multiply, you should get that your answer to this question is 864
Hope this helps!