Ineed with number 9. what do i do? show work

I would say "B"

blue chairs to red chairs is 2 to 5

so as a fractoon blue chairs are 2/7 and red chairs are 5/7.

since it is out of 7 i divide the total number of chairs by 7

a) 21/7= 3

3(2):3(5)

6:15 and this simplifies to 2:5

b)30/7 i would say would not work since it doesn't multiply into 30

c)28/7=4
4(2):4(5)
8:20 and this also simply to 2:5

d) 35/7=5
5(2):5(5)
10:25 this aswell simplifies to 2:5

so "B" is your answer since ut won't work

Its equal to d=7.07in