Question 1107937
Three sisters, Amy,Beth, and Carly are different ages. 
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Amy is 7 years older than Beth. 
<pre>
A = B+7
</pre>
Carly is twice the age of Beth. 
<pre>
C = 2B
</pre>
The sum of their ages is 47
<pre>
A+B+C = 47
</pre>
What are their ages?
<pre>
Substitute B+7 for A and 2B for C in

 A  + B +  C = 47

B+7 + B + 2B = 47

Simplify and solve for B.
Then to get A, substitute what you got for B
in A = B+7.
Then to get C, substitute what you got for B
in C = 2B.

Edwin</pre>