One car traveling at 30 mph and another car traveling at 40 mph left from the same place at the same time and traveled in opposite directions. how long will it take before the cars are 630 miles apart? one car traveling at 30 mph and another car traveling at 40 mph left from the same place at the same time and traveled in opposite directions. how long will it take before the cars are 630 miles apart?

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