Dan is 18 years old. In 6 years he will be 4/5 the age of his brother Nick. How old will
Nick be in 4 years?
years old

28

Step-by-step explanation:

18+6=24

24/1=4/5

6/1=5/1=30

Nick is 30 in 6 years

30-2

Nick is 28 in 4 years

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

a=24; b=12

step-by-step explanation:

a/b=2: 1

a=2b

36/(1+2)=12

b=12

a=24