Question 9 - Figure it out - Page 185 to 189 - Chapter 7 Class 7 - Finding the Unknown (Ganita Prakash II)

Transcript

Question 9 In a restaurant, a fruit juice costs ₹15 less than a chocolate milkshake. If 4 fruit juices and 7 chocolate milkshakes cost ₹600, find the cost of the fruit juice and milkshake.Let Cost of chocolate milkshake = ₹ x Given that a fruit juice costs ₹15 less than a chocolate milkshake So, we can write Cost of fruit juice = Cost of Chocolate milkshake – 15 = x – 15 Also, given that 4 fruit juices and 7 chocolate milkshakes cost ₹600 So, we can write 4 × Cost of fruit juice + 7 × Cost of Chocolate milkshake = ₹ 600 Putting values 4 × (x – 15) + 7 × x = 600 4(x – 15) + 7x = 600 Opening brackets 4 × x – 4 × 15 + 7x = 600 4x – 60 + 7x = 600 (4x + 7x) – 60 = 600 11x – 60 = 600 Putting –60 on right side, it becomes +60 11x = 600 + 60 11x = 660 Putting 11 on right side, so it becomes division x = 660/11 x = 60 Thus, Cost of chocolate milkshake = x = ₹ 60 Cost of fruit juice = x –15 = 60 – 15 = ₹ 45