Oscar says to Vanesa: "I am five times the age you were when I was the age you are; and when you are the age I am, our ages will add up to 72 years." How old is Vanessa? Please

18

Step-by-step explanation:

Let's say x is Oscar's age, and y is Vanessa's age.

When Oscar was Vanessa's age, Vanessa was y−(x−y) = 2y−x years old.  Oscar is five times older than this:

x = 5 (2y − x)

x = 10y − 5x

6x = 10y

3x = 5y

When Vanessa is Oscar's age, Oscar will be x+(x−y) = 2x−y years old.  The sum of their ages will by 72.

2x−y + x = 72

3x − y = 72

Substituting:

5y − y = 72

4y = 72

y = 18

Vanessa is 18.  Which means Oscar is 30.

Let's check our answer.  When Oscar was 18, Vanessa was 6.  Oscar is 5 times older than that (30).  When Vanessa is 30, Oscar will be 42, and their ages will add up to 72.

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