gina is 9 years younger than her sister, bridgette. two years ago, bridgette was twice as old as gina was. how old is gina

Question

I need help answering this math problem 

Answer 1

G is Gina now

B is Bridgette now

G-2 is Gina 2 years ago

B-2 is Bridgette 2 years ago

g=b-9

b-2=2(g-2)

substitute the 1st equation 

 

b-2=2(b-9-2)

b-2=2b-22

b=20

g=20-9=11

 

it checks bc 2 years ago g was 9 and B was 18. 

 

Answer 2

G = Gina's present age

B = Bridgette's present age

 

G = B - 9

 

Two years ago, Gina's age was G - 2, Bridgette's was B-2, and was twice Gina's age then.

 

B - 2 = 2(G - 2)

 

We must solve this system of equations:

 

(i)   G = B - 9
(ii)  B - 2 = 2(G - 2)

 

Take G from (i) and plug it into (ii) to get B.

 

B - 2 = 2[(B - 9) - 2]

 

-2 + 18 + 4 = B

 

B = 20

G = B - 9 = 11