A scheme starts in a village only if at least 75% of its 240 households sign up. So far 168 households have signed up. What per cent of the 240 households must still sign up for the scheme to start?

The scheme needs 75% of 240 = 180 households, and 168 have signed, so 12 more are needed. The phrase 'of the 240 households' fixes 240 as the base: 12/240 = 0.05 = 5%. 7.14% is 12/168, measured against those who have already signed - the wrong base. 70% is 168/240, the share signed up so far. 25% is 100 - 75, the share that need not sign up at all.