Oranges are to be transferred from larger boxes into smaller boxes. When a large box is emptied, the oranges from it fill two smaller boxes and still $10$ oranges remain outside. If the number of oranges in a small box are taken to be $x$, what is the number of oranges in the larger box?

Look at the following matchstick pattern of squares. The squares are not separate. Two neighbouring squares have a common matchstick. Observe the patterns and find the rule that gives the number of matchsticks in terms of the number of squares.

(a)

(b)

(c)

(d)

(Hint: If you remove the vertical stick at the end, you will get a pattern of Cs.)

The following figures gives a matchstick pattern of triangles. Find the general rule that gives the number of matchsticks in terms of the number of triangles.

(a)

(b)

(c)

(d)

The diameter of a circle is a line which joins two points on the circle and also passes through the centre of the circle. (In the below figure $\mathrm{AB}$ is a diameter of the circle; $\mathrm{C}$ is its centre). Express the diameter of the circle ($d$) in terms of its radius ($r$).