A no-interest loan of £1,600 from a family member is repaid at £200 a month. Which rule gives the balance owed, L, after m months, and when is it cleared?

1. The balance starts at £1,600 before any month has passed, so 1600 is the starting value. 2. Each month knocks £200 off, so the rate of change is minus 200 pounds per month. 3. That gives the rule L = 1600 - 200m. 4. Setting L to zero gives 200m = 1600, so m = 8 months. 5. Option B has the right rule but halves the answer, which would leave £800 still owing. 6. Option A adds the repayments to the debt instead of taking them off. _Source: OpenStax College Algebra (CC BY 4.0), Ch 4 "Linear Functions", section 4.2 Modeling with Linear Functions_