Lizzy: Jack and Jill are friends who borrow from each other often. Last week Jack borrowed $1200 from Jill, which he promised to pay back with an interest of 10%. How much will Jack pay back?.
Me: Hmmm, let me think. I think this is the detailed solution:
The interest on the loan is 0.1 * 1200 = $120. The total amount Jack needs to pay back is 1200 + 120 = 1320. Final answer: 1320.