On his 10th birthday, Tom's allowance was doubled. When he turned 12, his allowance increased by $10 to $34 per month. What was Tom's allowance before his tenth birthday?

Answer 1

34 per month minus 10 per month is 24. 24 divided by 2 (it was doubled on his 10th Bday) is 12 per month. Just do it backwards.

answer is 12 per month.

Answer 2

Here is another way.

2x + 10 = 34

Solve for x.