Question 50073
It's not a stupid question! The distributive property lets you factor out common multiples in an expression. In this case, your only common factor would be 2 (since 2 and 12 are both divisible by 2). Just divide two out of the expression and place it outside:

2s + 12r = (2*1)s + (2 * 6)r = 2(s + 6r)

Good luck in your class!