We divide the total set into several sub-sets (subgroups) that contain the exact same number of members. This way we know the number of total members by adding the number of total subsets.
-11 = a + 7 Given
-7 -7 Subtract 7 on each side to cancel out +7 and isolate variable
-18 = a Answer
Prove.
-11 = -18 + 7 Plug in variable value
-11 = -11
True.
Answer:
5
Step-by-step explanation:
