Question

if 4a + 5b + 9c = 36 and 7a + 9b + 17c = 66 then find a + b + c
Please help me.

Answer 1

a + b + c = 6 .. solution is in the pic :)

Answer 2

$Given \: 4a + 5b + 9c = 36 \: ---(1)$

$7a + 9b + 17c= 66\: ---(2)$

/* Multiplying equation (1) by 2 , we get */

$8a + 10b + 18c = 72 \: ---(3)$

/* Subtract Equation (2) from equation (3) , we get */

$8a + 10b + 18c - (7a + 9b + 17c )= 72 - 66$

$\implies 8a + 10b + 18c - 7a - 9b - 17c = 6$

$\implies a + b + c = 6$

Therefore.,

$\red { Value \:of \: a + b + c}\green { = 6}$

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