Girls are 1 unit; boys are twice as many, so 2 units. Altogether that is 3 units = 1740 pupils.

Girls?Boys111740

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

  1. Girls + Boys = 3 units → 1740
  2. 1 unit → 1740 ÷ 3 = 580

There are 580 girls.

Check: 580 girls + 1160 boys = 1740 pupils. ✓