Annabelle collected a weekly allowance of $30. She spent a third of it buying junk food, then spent another $8 on sweets. Out of guilt she decides to save the rest. How much did she save? Think carefully first, then make a decision:
A third of $30 is $30 * (1 / 3) = $10. She spent $10 from $30 leaving $30 - $10 = $20. She spent another $8 leaving $20 - $8 = $12 which she saved. So, the answer is 12.