Simplifying means collecting the terms that are alike and leaving everything else alone. Terms with the same letter are alike, so 5a and 2a add to 7a. Plain numbers are alike with each other, so 8 and 3 combine. A letter term and a plain number are never alike, which is why 7a + 5 is as short as it goes. Watch the signs: the minus in front of a number belongs to that number and travels with it. At P6 there are no brackets to expand — the whole job is grouping.
Worked example
Problem Simplify 5a + 8 + 2a − 3.
Group the like terms first: the a terms are 5a and 2a, and the plain numbers are 8 and 3.
Add the a terms: 5a + 2a = 7a.
Now the numbers: 8 − 3 = 5, so the expression simplifies to 7a + 5.
Watch out Adding all four numbers to get 12a is the commonest slip. Only LIKE terms can be joined.