Okay, here we go.
So, given the formula, we can just plug in the numbers on the number lines. So for example:
On the first graph, it starts at 4 and goes to 5. Let's plug those in:
-6(4)+42<24
-24+42<24
18<24
18 is less than 24, so this is true so far.
moving on:
-6(5)+42<24
-30+42<24
12<24
true, again. The first graph seems correct. Let's check our answers by using the third graph where the numbers 3,2, and 1 are checked.
-6(3)+42<24
-18+42<24
24<24
24 is equal to 24, not less than, so the third graph is wrong.
Knowing this, we can use the process of elimination. We know 4 and 5 fit the equation and 3, 2, and 1 don't. This means that the graph with 4 and 5 marked is the correct one aka the first graph
Hopefully this is correct and I helped at all :)