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the sum of sid's and Sue's ages is 30. If 8 years ago Sid was as old as Sue was 2 years ago, then how old is Sue now?

 Feb 8, 2019
 #1
avatar+98090 
+2

Let Sid's age be A

Then Sue's age is  30 - A

 

And 8 years ago....Sid's age was A - 8

And 2 years ago, Sue's age was 30 - A - 2   =   28 - A

 

And we know that

A - 8  = 28 - A      add A, 8 to both sides

 

2A = 36     divide both sides by 2

 

A = 18

 

So... Sue is   30 - 18   =  12 

 

 

cool cool cool

 Feb 8, 2019
 #2
avatar+17269 
+2

Since we are looking for Sue's age now, let x = Sue's age now

 

x+SID =30

    and

SID-8 = x-2    re-arrange

SID = x+6     sub into the first equation

x  +   x+6 = 30

x = 12

 Feb 9, 2019

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