Question

3a + 6b + 9c = 24, 9a + 7b + 5c = 28, a + b + c = ?
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Answer 1

Answer:

11a+13b+14c=52 .............????

Answer 2

Answer:

a+b+c=4

Step-by-step explanation:

3a+6b+9c=24;9a+7b+5c=28

3(a+2b+3c)=24

a+2b+3c=8___(1)

9a+7b+5c=28___(2)

Adding both (1)&(2)

We get, 10a+9b+8c=36___(3)

Substracting both (1)&(2)

We get, 8a+5b+2c=20___(4)

From (3)&(4);

Now multiplying equation (3) with 1 and equation (4) with 4,

We get,

10a+9b+8c=36

32a+20b+8c=80

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-22a-11b=-44

So, we get, b=-2a+4___(5)

Putting (5) into equation (4)

8a+5(-2a+4)+2c=20

From this, a=c__(6)

As we have to find, a+b+c___(7)

Putting the value of b from (5) & c from (6) in (7)

a+b+c= a+(-2a+4)+a = 4___Answer.