Step 1: Set up the investment split. TCI=100, WC=15, FCI=85, i=0.0495, n=15.
Step 2: Discount and annuity factors. (1.0495)^15≈2.0641, PVIFA=10.415.
Step 3: NPV=0 breakeven condition.
\[ 100 = A(10.415) + 15(0.4845) \]
Step 4: Solve for A.
\[ A = 92.733/10.415 = 8.904 \]
Step 5: Convert to payback period.
\[ P_{b,max} = 85/8.904 \approx 9.55\ \text{years} \]
Step 6: Choose the largest listed value not exceeding 9.55 years.
\[ \boxed{P_{b,max} = 8\ \text{years}} \]