Choice D is the correct answer. Let $r$ = regular tickets and $v$ = VIP tickets.

System: $\begin{cases} r + v = 120 \\ 5r + 15v = 1000 \end{cases}$

Step 1: From first: $r = 120 - v$

Step 2: Substitute: $5(120 - v) + 15v = 1000$$600 - 5v + 15v = 1000$$10v = 400$$v = 40$

Solution: 40 VIP tickets (and 80 regular tickets)

Verification: $80 + 40 = 120$ ✓ and $5(80) + 15(40) = 400 + 600 = 1000$ ✓

💡 Strategic Tip: Ticket problems combine quantity and revenue equations.

**Other choices fail verification.