At first Money leads Anita by $520. Money gives Anita some money: every $1 he gives drops his lead by $2 (he loses $1, she gains $1). The lead falls from $520 to $100.

Anita?Moneysame$520lead = $520Money = $1200

Plain numbers are given; italic underlined numbers are worked out.

  1. Lead must fall → $520 − $100 = $420
  2. Each $1 given closes the gap by $2 → gift = $420 ÷ 2 = $210

Money gave Anita $210.

Check: Money $1200−$210=$990, Anita $680+$210=$890, lead $990−$890=$100. ✓