For this one, set bot angles equal to 180 like this:
2x-9+5x-7=180
The reasoning is a straight line has an angle of 180 and the two angles being in opposite positions, you can set them equal to 180.
Now combine like terms:
2x+5x=7x
-9-7=-16
Now your new problem looks like:
7x-16=180
Next isolate the x:
7x-16+16=180+16
7x=196
Now divide by 7 to make the x by itself:
7x/7=196/7
This comes out even to x=28.
Now since it is a word problem, higher math says to answer it in the same format:
To make m and n congruent, x has to equal 28.
Hope this helps!
