<PRE><B>Question 936779</B>
Let x be the unknown age of Shelly
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x+x+2+x+7=21
3x+9=21(subtract 9)
3x=12 (divide by 3)
x=4
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Therefore Shelly is 4 years old. 
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Since Shelly is 7 years younger than Ruby and Paula is only 5 years younger than Ruby; Paula is 2 years older than Shelly.
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Therefore Paula is 6
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Since Ruby is 7 years older than Shelly, Ruby must be 11.</PRE>