Method of Substitution to Find the Solution of a Pair of Linear Equations
Ravi and Raj ...
Question
Ravi and Raj together have 45 marbles. Both of them lost 5 marbles each, and the product of the number of marbles they now have is 124. Find out the number of marbles they had to start with.
A
36 and 9
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B
40 and 5
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C
20 and 25
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D
14 and 31
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Solution
The correct option is A36 and 9 Let Ravi have x, marbles. Hence Raj has 45−x marbles. Now applying the above condition, we get (x−5)(45−x−5)=124 (x−5)(x−40)=−124 x2−45x+200+124=0 x2−45x+324=0 (x−36)(x−9)=0 Hence x=36 or x=9 Thus if one had 9 marbles then the other had 36 marbles.