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Explanation
- A pineapple costs Rs. 7 each.
- A watermelon costs Rs. 5 each.
- X spends Rs. 38 on those fruits.
Let suppose “p” denotes pineapple and “w” denotes watermelon.
Now;
7p + 5w = 38
7p = 38 – 5w
p = (38 – 5w)/7
Clearly, p is a whole number only when (38 – 5w) is divisible by 7. This happens when w = 2 (and p = 4).
To Find
Number of pineapples purchased = ?
Solution
Let suppose “p” denotes pineapple and “w” denotes watermelon.
Now according to the given condition;
7p + 5w = 38
7p = 38 – 5w
p = (38 – 5w)/7
Suppose w = 0
p = (38 – 0)/7 = 38/7 (p is not a whole number here)
Suppose w = 1
p = (38 – 5)/7 = 33/7 (p is not a whole number again)
Suppose w = 2
p = (38 – 10)/7 = 4 (that’s the result we want)
Number of pineapples purchased = 4 answer
Conclusion
A pineapple costs Rs. 7 each. A watermelon costs Rs. 5 each. X spends Rs. 38 on those fruits. The number of pineapples purchased are 4.
