Time taken by Michael to colour the picture = 7/12
Time taken by Vaibhav to colour the picture = 3/4
Converting both fractions in like fractions, 7/12 and 3×3/4×3 = 9/12
Here, 7/12<9/12 ⇒ 7/12<3/4
Thus, Vaibhav worked longer time.
Vaibhav worked longer time by 3/4 – 7/4 = 9-7/12 = 2/12 = 1/6 hour.
Thus, Vaibhav took 1/6 hour more than Michael.

Exercise 2.1 Question 5, 6, 7, 8

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https://www.tiwariacademy.com/ncert-solutions/class-7/maths/chapter-2/