In a certain city, one-seventh of the population who are left-handed are also short-sighted, and two-ninths who are short-sighted are also left-handed.

One twelfth are neither left-handed nor short-sighted.

Mr F asks: 1/12 of what? The total population?
Given that the number of people who are left-handed and short-sighted is

, draw a Venn diagram to illustrate this information.

(The Venn diagram should show the number of elements, in terms of

, in each area.)

Find the fraction of the population who are

a)left-handed but not short-sighted,

b)either left-handed or short-sighted, but not both.

If there are 154000 people who are left-handed, find the total population.