Lizzy: Sarah starts saving $5.00 a week for 4 weeks. Then she saves $10.00 a week for the next 4 weeks. Then she saves $20.00 a week for the next 4 weeks. How much money has she saved over 12 weeks?.
Me: Hmmm, let me think. I think this is the detailed solution:
She starts with $5.00 a week for 4 weeks so that's 5 * 4 = $20.00. Then she bumps it up to $10.00 a week for 4 weeks so that's 10 * 4 = $40.00. After that, she saves $20.00 a week for 4 weeks so that's 20 * 4 = $80.00. Over 12 weeks she has saved 20 + 40 + 80 = $140.00. Final answer: 140.