Question 4 - Figure it out - Page 102 to 105 - Chapter 4 Class 7 - Expressions using Letter-Numbers (Ganita Prakash)

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Question 4 Radha is preparing for a cycling race and practices daily. The first week she cycles 5 km every day. Every week she increases the daily distance cycled by ‘z’ km. How many kilometers would Radha have cycled after 3 weeks?Now, we do it week wise Week 1 Number of km cycled daily in 1st week = 5 km So, Distance travelled in 1st week = Number of days × 5km = 7 × 5 = 35 km Week 2 Number of km cycled daily in 2nd week = (5 + z) km So, Distance travelled in 2nd week = Number of days × (5 + z) km = 7 × (5 + z) = 7 × 5 + 7z = 35 + 7z Week 3 Number of km cycled daily in 3rd week = (5 + z + z) km = (5 + 2z) km So, Distance travelled in 3rd week = Number of days × (5 + 2z) km = 7 × (5 + 2z) = 7 × 5 + 7 × 2z = 35 + 14z = 7 × (5 + 2z) = 7 × 5 + 7 × 2z = 35 + 14z Therefore, Total distance after 3 weeks = 35 + (35 + 7z) + (35 + 14z) = (35 + 35 + 35) + (7z + 14z) = 105 + 21z km