SOLUTION: Hello there. I have been wondering how to do this question all day, you see algebra is not my strongest point and I was hoping if you could help me. Here is the question Look

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Question 1062309: Hello there. I have been wondering how to do this question all day, you see algebra is not my strongest point and I was hoping if you could help me.
Here is the question
Look at these simultaneous questions.
a+b+c=10
a+b-c=3
Find the value of a+b+3c

Thank you very much.

Found 2 solutions by Boreal, MathTherapy:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
a+b+c=10
a+b-c=3
solve for c in each
c=10-a-b
c=a+b-3
Set those two equal to each other
a+b-3=10-a-b
2a+2b=13
a+b=6.5, dividing both sides by 2
now substitute that into both equations
6.5+c=10
6.5-c=3
Both will give c=3.5
Therefore, a+b+3c=6.5+3(3.5)=6.5+10.5=17

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Hello there. I have been wondering how to do this question all day, you see algebra is not my strongest point and I was hoping if you could help me.
Here is the question
Look at these simultaneous questions.
a+b+c=10
a+b-c=3
Find the value of a+b+3c

Thank you very much.
a + b + c = 10 -------- eq (i)
a + b – c = 3 --------- eq (ii)
2c = 7 ------- Subtracting eq (ii) from eq (i)
c = 7%2F2, or 3.5

a + b + 3.5 = 10 -- Substituting 3.5 for c in eq (i)
a + b = 6.5 ------- eq (iii)
OR
a + b - 3.5 = 3 --- Substituting 3.5 for c in eq (ii)
a + b = 6.5 ------- eq (iv)

As seen a + b = 6.5, so