if a+b = 65, a+c=63 and a+d=45 what will be the value of "a" if a+b+c+d=118



a + b = 65 (eqn 1)

a + c = 63 (eqn 2)

a + d = 45 (eqn 3)

a + b + c + d = 118 (eqn 4)



Adding eqns (1), (2), and (3), we get

3*a + b + c + d = 65 + 63 + 45 = 173

So, b + c + d = 173 - 3*a   (eqn 5)



Substituting for (b+c+d) in eqn (4)



a + 173 - 3*a = 118

2*a = 173 - 118 = 55

a = 

Now we can find b, c and d from the first 3 equations

b = 65 - a = 65 - 27.5 = 

c = 63 - a = 63 - 27.5 = 

d = 45 - a = 45 - 27.5 = 



Check for correctness:

a + b + c + d = 27.5 + 37.5 + 35.5 + 17.5 = 118 (correct!)



:)

 

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