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All triangles have the same value, and all circles have the same value. What is the sum of three circles? \begin{align*} \Delta + \bigcirc + \Delta + \bigcirc + \Delta&= 21\\ \bigcirc + \Delta+\bigcirc+\Delta+\bigcirc &= 19\\ \bigcirc + \bigcirc + \bigcirc &= \ ? \end{align*}

 Jul 24, 2021
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3T  + 2C  =   21     ⇒    6T  + 4C  =      42

2T  + 3C  =  19     ⇒    -6T  -  9C  =   - 57

 

Add the last  two  equations

 

-5C  =  - 15

 

C  =   -15  / -5     =    3

 

So

 

3C  =  3 (3) =   9

 

cool cool cool

 Jul 24, 2021

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