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Carlos is five years older than twice his sister's age. Carlos is 13. Which equation and solution correctly identifies his sister's age?

 Apr 30, 2014

Best Answer 

 #1
avatar+33658 
+5

We start by giving a label, say x, to the sister's age (you can think of x as a label on a box inside which is the number representing her age).  We have to use the information we are given in order to calculate x (the number in the box).

We are told that the age of Carlos is 2*x + 5 and that this equals 13, so the equation is

2*x + 5 = 13.

Subtract 5 from both sides of this equation

2*x = 8

Divide both sides by 2

x = 4

So his sister is 4 (this is the number in the box labelled x) 

 Apr 30, 2014
 #1
avatar+33658 
+5
Best Answer

We start by giving a label, say x, to the sister's age (you can think of x as a label on a box inside which is the number representing her age).  We have to use the information we are given in order to calculate x (the number in the box).

We are told that the age of Carlos is 2*x + 5 and that this equals 13, so the equation is

2*x + 5 = 13.

Subtract 5 from both sides of this equation

2*x = 8

Divide both sides by 2

x = 4

So his sister is 4 (this is the number in the box labelled x) 

Alan Apr 30, 2014

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