Example 5 - Chapter 4 Class 7 - Expressions using Letter-Numbers (Ganita Prakash)

Transcript

Example 5 Here is a table showing the number of pencils and erasers sold in a shop. The price per pencil is c, and the price per eraser is d. Find the total money earned by the shopkeeper during these three days.Given Price per pencil = c Price per eraser = d Now, we do it day by day Day 1 5 pencils and 4 erasers were sold Now, Cost of 5 pencils = 5 × c = 5c Cost of 4 erasers = 4 × d = 4d Thus, Amount earned on Day 1 = 5c + 4d Day 2 3 pencils and 6 erasers were sold Now, Cost of 3 pencils = 3 × c = 3c Cost of 6 erasers = 6 × d = 6d Thus, Amount earned on Day 2 = 3c + 6d Day 3 10 pencils and 1 eraser were sold Now, Cost of 10 pencils = 10 × c = 10c Cost of 1 eraser = 1 × d = d Thus, Amount earned on Day 3 = 10c + d Therefore, Total Amount earned during 3 days = Amount earned on Day 1 + Amount earned on Day 2 + Amount earned on Day 3 = (5c + 4d) + (3c + 6d) + (10c + d) Grouping c together, and grouping d together = (5c + 3c + 10c) + (4d + 6d + d) = 18c + 11d