The first five terms of a pattern are given below.

which expression can be used to determine the nth term of the pattern?

a.32 - n
b.30 + n
c.29 + 2n
d.33 - 2n

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.