A pineapple costs Rs. 7 each. A watermelon costs Rs. 5 each. X spends Rs. 38 on these fruits. The number of pineapples purchased is - Sri Chaitanya Infinity Learn Best Online Courses for NCERT Solutions, CBSE, ICSE, JEE, NEET, Olympiad and Class 6 to 12

A
$2$
B
$3$
C
$4$
D
Data inadequate

Solution:

Concept- Using concepts of linear equation in two variables the cost of a pineapple and cost of a watermelon can be determined. X spends Rs. 38 on these fruits. The cost of ‘m’ pineapples is Rs. m and the cost of ‘n’ watermelons is Rs. n. The total amount on these fruits is

7 m + 5 n = 38

Cost of each pineapple = 7

Cost of each watermelon = 5

Total amount on these fruits is,

7 m + 5 n = 38

7 m = 38 - 5 n

m = \frac{38 - 5 n}{7}

n = 2

.
Changing the value of n in the equation above,

m = \frac{38 - 5 \times 2}{7}

m = \frac{28}{7}

m = 4

Hence, option 3 is correct.

Solution:

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