+0  
 
0
131
3
avatar

Jack is 13 years older than Bao. In 8 years, he will be twice as old as Bao. How old is Jack now?

 Jun 24, 2020
 #1
avatar+134 
+2

So we can express jacks curent age as x, and bao's current age as x-13. It says that 'In 8 years, he will be twice as old as Bao" and we can express that as x+8=2(x-13+8) which we can simplify to x+8=2x-10 from here x=18, so jack is curently 18.

 Jun 24, 2020
 #2
avatar+28021 
0

j = 13 + b         and in 8 years   j +8 = 2(b+8)   (or  (j+8)/2 -8=b)

 

j = 13 +  (j+8)/2 - 8

1/2 j = 13 +4-8

j = 18        b = 5                  in 8 years    j = 26   b = 13

 Jun 24, 2020
edited by ElectricPavlov  Jun 24, 2020
 #3
avatar+2175 
0

Let's make two equations!

 

Let j=Jack's age

Let b=Bob's age

 

j-13=b

j+8=2(b+8)

 

--Expand--

j-13=b

j-8=2b

 

--Subtract equations--

-5=-b

b=5

(Bob is 5 years old now)

18-13=5

 

So, Jack is 18 years old!

 Jun 24, 2020

18 Online Users

avatar
avatar