At a cafe, Rama bought drinks for her 7 friends at ₹240. Some of them wanted coffee, while others wanted black tea. A regular cup of coffee cost ₹40 and a regular cup of black tea cost ₹30. How many cups of tea did she purchase?

Question

Accepted Answer

Let the number of cups of coffee be x and the number of cups of tea be y.

Given:
Total friends = 7, so x + y = 7  ...(1)
Cost of coffee = ₹40 per cup
Cost of tea = ₹30 per cup
Total cost = ₹240

So, 40x + 30y = 240  ...(2)

From equation (1), x = 7 - y
Substitute in equation (2):
40(7 - y) + 30y = 240
280 - 40y + 30y = 240
280 - 10y = 240
-10y = 240 - 280
-10y = -40
y = 4

But 4 is not the correct answer according to the options and the answer key. Let's re-check calculations:

Equation (1): x + y = 7
Equation (2): 40x + 30y = 240

Substitute x = 7 - y into (2):
40(7 - y) + 30y = 240
280 - 40y + 30y = 240
280 - 10y = 240
-10y = -40
y = 4

So y = 4 cups of tea.

Since the answer key says 5, let's verify if y=5 satisfies the conditions:
If y=5, then x=2
Cost = 40*2 + 30*5 = 80 + 150 = 230 (not 240)

If y=3, x=4
Cost = 40*4 + 30*3 = 160 + 90 = 250 (not 240)

If y=6, x=1
Cost = 40*1 + 30*6 = 40 + 180 = 220 (not 240)

If y=5, cost is 230, close but not 240.

Re-examining the problem: It says Rama bought drinks for her 7 friends at ₹240. So total cups = 7.

Try y=5:
Total cost = 40*(7-5) + 30*5 = 40*2 + 150 = 80 + 150 = 230
Try y=6:
Total cost = 40*1 + 30*6 = 40 + 180 = 220
Try y=3:
Total cost = 40*4 + 30*3 = 160 + 90 = 250
Try y=4:
Total cost = 40*3 + 30*4 = 120 + 120 = 240

So y=4 cups of tea is correct.

Therefore, the correct answer is 4 cups of tea.

Answer

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