The price of 80 apples is equal to that of 120 oranges. The price of 60 apples and 75 oranges together is Rs. 1320. The total price of 25 apples and 40 oranges is

A. Rs. 660

B. Rs. 820

C. Rs. 780

D. Rs. 620

Solution:

Let price of one apple = a

price of one orange = b

Price of 80 apples = Price of 120 oranges

⇒ 80a = 120b

⇒ 2a = 3b

⇒ b = 2a / 3 ⋯ ( 1 )

Price of 60 apples + Price of 75 oranges = Rs. 1320

⇒ 60a + 75b = 1320

⇒ 4a + 5b = 88

⇒ 4a + 5 (2a) / 3 = 88 [∵ substituted value of b from ( 1 ) ]

⇒ 12a + 10a = 88 × 3

⇒ 6a + 5a = 44 × 3

⇒ 11a = 44 × 3

⇒ a = 4 × 3 = 12

b = 2a / 3 = 2 × 12 / 3 = 8

Total price of 25 apples and 40 oranges

= 25a + 40b

= 25 × 12 + 40 × 8

= 300 + 320

= 620

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