BRAINLIEST TO WHOEVER ANSWERS QUICKEST AND IS RIGHT.

anaalyze the problem

first term: -1

common difference: +9 (8-(-1) is 9)

so, an=-1+9n-9

answer is an=9n-10, with n bigger or equal to one

sixth term,plug in 9(6)-10=54-10=44

tenth term, plug in 9(10)-10=90-10=80

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional