haresh went to buy fruits.she bought 1 apple , 3 bananas , 5 oranges and paid 21 rupees.another person bought 7 apple ,5 bananas , 3 oranges and paid 51 rupees.if i want to buy 1 apple, 1 banana , 1 orange then how much i have to pay?  Answers
A) 8
B) 9
C) 10
D) 11
E) 7

Rationale: there can be multiple possible rates of apple , banana and orange to satisfy given conditions , but cost of 1 apple , 1 banana , 1 orange will be rs 9 . 1 x + 3 y + 5 z = 21 . . . . . . . . ( 1 ) 7 x + 5 y + 3 z = 51 . . . . . . . . ( 2 ) adding ( 1 ) and ( 2 ) , we get 8 x + 8 y + 8 z = 72 8 * ( x + y + z ) = 72 x + y + z = 9 answer : b
Answer: B