This is the concept of algebra, to get the inequality we proceed as follows; Erma subtracted 8 from both sides and divided both sides by 8 so that we can get the value of the unknown. The the properties used were:
Subtraction properties of inequality, which states that: if a<b, then a-c<b-c
Division properties of inequality, which states that: if a<b, then a/c=<b/c