If 3 X + 7 Y = 75, 5 X – 5 Y = 25, then the value of (X + Y) =

(a) 17
(b) 16
(c) 18
(d) 15

Anurag Mishra Professor Asked on 10th February 2016 in Maths.
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  • 1 Answer(s)

    Answer: (a) 17 

    Solution:-
    3 X + 7 Y = 75 ……………… (1)
    5 X – 5 Y = 25 …………………..(2)

    Equation (2) divide by 5 and multiply by 7,
    Then, 7 X – 7 Y = 35 …………….. (3)

    Add equation (1) & (3) ,
    3 X + 7 Y + 7 X – 7 Y = 75 + 35
    10 X = 110
    X = 110/10
    X = 11

    Put the value of X = 11, in equation (1),
    Then, 3 x 11 + 7 Y = 75
    7 Y = 75 – 33
    7 Y = 42
    Y = 42/7
    Y = 6

    So, the value of X + Y = 11 + 6
    = 17

    Hence, the correct answer is option (a) 17.

    Anurag Mishra Professor Answered on 11th February 2016.
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