An elevator has a capacity of 12 adults or 20 children. How many adults can board the elevator with 15 children?

Step-by-step solution

As per the question : Let the weight of one adult = x And the weight of one child = y Then, total capacity = 12 × x   = 20 × y ⇒ y = 3 x 5 Let A be the number of adults that board the elevator with 15 children. According to the question : 15 y + A x = 12 x 15 × 3 x 5 + A × x   =   12 × x ⇒ 9 x + A x = 12 x ⇒ 9 + A = 12 ⇒ A = 3 Hence, 3 adults can board the elevator with 15 children.