The distributive property is used for this purpose. The factor outside parentheses (2) multiplies each of the terms inside parentheses (q, 3).
2(q +3) = 2·q +2·3 = 2q +6
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<em>Additional comment</em>
It might help to think of the parentheses as a "bag" containing one "q" and 3 tokens. The number outside parentheses tells you how many "bags" you have. Expanding the expression is equivalent to dumping out the bags and describing the total contents:
2(q +3) = (q +3) +(q +3) . . . . multiplication is the same as repeated addition
First you create a proportion (30/100=x/120). After you solve this, next you subtract this answer from 120. Then create a proportion for 40% (40/100=x/120). Then add this number to the first answer you got when you subtracted the answer from your first proportion from 120.
