We are trying to find the number that when added to 19, gives us less than 42. We can set up this simple inequality:
19 + x < 42
Now, subtract 19 from both sides:
x < 23
Our number can be anything less than 23.
The linear combination method is the same as the elimination method. Let's multiply the second equation by -2 so the x terms cancel each other out. When we do that we get a system of

and

. The x-terms cancel each other out giving us

and y = -3. Now sub -3 into one of the equations to solve for x. x+2(-3)=-4, and x - 6 = -4. x = 2. So the solution for our system is (2, -3)
Answer:
x = 4
Step-by-step explanation:
9(x - 2) = 18
9x - 18 = 18
9x = 18 + 18
9x = 36
x = 36/9
x = 4