Question 1073788
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Given that
5a - 7b + 3c = 19, 
 2a - 4b + c = 77,
determine the value of a+b+c. Thank you.
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<pre>
5a - 7b + 3c = 19,      (1)
2a - 4b +  c = 77.      (2)


Multiply equation (2) by 2 (both sides). Write the updated system:

5a - 7b + 3c =  19,     (1)
4a - 8b + 2c = 154.     (2')

Subtract equation (2') from equation (1) (both sides). You will get

 a + B + c = 154-19 = -135.


<U>Answer</U>.  a + b + c = -135.
</pre>

Solved.