This would be called an ANGLE.
Hopefully this helps!
The answer is c). (x-5)(x-7)
You need to isolate x, which means you need to get it alone. 16x and 11x are like terms because they both have an x, do subtract them. 16-11=5. So 15 = 5x
Then to turn 5x into x, divide by five. This is because 5/5 is 1, and 1x is x. Divide both sides, so
X = 3
Let v = number of video's she bought
Let c = number of CD's she bought
v+c=16
1495v+1688c=9355
Multiply both sides of (1) by 1495
and subtract (1) from (2)
-1495v-1495c=-8970
193c=386
c=2h