Question
Levi has 20 pens. All of the pens are either blue or black, and there are 12 more blue pens than black pens. How many blue pens does Levi have?
Answers
oobleck
If there are x blue pens, then there are x-12 black pens.
x + x-12 = 20
find x
x + x-12 = 20
find x