Let the number of article produced on the day be ‘a’.
Given, it was observed on a particular day that the cost of production of each article (in rupees) was 3 more than twice the number of articles produced on that day.
Cost of production of each article = 2a + 3
Given, cost of production was Rs. 90
⇒ a(2a + 3) = 90
⇒ 2a2 + 3a – 90 = 0
⇒ 2a – 12a + 15a – 90 = 0
⇒ 2a(a – 6) + 15(a – 6) = 0
⇒ (2a + 15)(a – 6) = 0
⇒ a = 6
Cost of each article = 2 × 6 + 3 = Rs. 15