Jono = 1 unit, Mark = 3 units. Together that is 4 units = $1300. Mark has 2 units more than Jono.

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

1. 4 units → $1300
2. 1 unit → $1300 ÷ 4 = $325 (Jono)
3. Mark − Jono = 2 units → 2 × $325 = $650

Jono had $325; Mark had $650 more than Jono.

Check: $325 + $975 (Mark) = $1300; $975 − $325 = $650. ✓