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.
<pre>a + b + c = 10 -------- eq (i)
a + b – c = 3 --------- eq (ii)
2c = 7 ------- Subtracting eq (ii) from eq (i)
c = {{{7/2}}}, or 3.5

a + b + 3.5 = 10 -- Substituting 3.5 for c in eq (i)
a + b = 6.5 ------- eq (iii)
<b><u>OR</b></u>
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 {{{highlight_green(matrix(1,7, a + b + 3c, "=", 6.5 + 3(3.5), "=", 6.5 + 10.5, "=", highlight(17)))}}}</pre>