6. What is the value of $\frac{6}{12}-\frac{5}{12}+\frac{4}{12}-\frac{3}{12}+\frac{2}{12}-\frac{1}{12}%speech%the formula shown on the screen$?
9. One half of one third of one quarter of one fifth of a number is $2$. What is the number?
12.The diagram shows an equilateral triangle divided into four smaller equilateral triangles.
One of these triangles has itself been divided into four smaller equilateral triangles.
What fraction of the area of the large triangle has been shaded?