Let the number of sea shells found by sandy = x
So, the number of sea shells found by Anita = (x + 5).
The number of sea shells found by Shella = 2 (x + 5).
According to the question,
⇒ x + 2(x + 5) = 16
⇒ x + 2x +10 = 16
⇒ 3x + 10 = 16
Subtracting 10 from both sides, we get
⇒ 3x + 10 – 10 = 16 – 10
⇒ 3x = 6
Dividing both sides by 3, we get
⇒ 3x/6 = 6/3
⇒ x = 4
Thus, the number of sea shells found by Sandy = x = 4,
The number of sea shells found by Anita = x + 5 = 4 + 5 = 9,
The number of sea shells found by Shelia = 2 (x + 5) = 2 (4 + 5) = 2(9) = 18.