The figure shows the amount of water in two rectangular tanks, U and V, at first. Carl poured ¹₅ of the water from U into V to fill it to the top, without overflowing.

1. How much water was there in Tank U at first?
2. Carl then poured all the water from Tank V into Tank U. 7128 cm³ of water overflowed from Tank U. What was the height of Tank U?

(a)
Volume of water to fill Tank V
= 18 x 14 x 14
= 3528 cm<sup>3

1</sup>₅ of volume of water in Tank U at first = 3528 cm^3  
5₅ of volume of water in Tank U at first = 5 x 3528 = 17640 cm³

Volume of water in Tank U at first = 17640 cm³

Volume of water in Tank V at first
= 18 x 14 x 18
= 4536 cm³

Total volume of water in Tank U and Tank V 
= 17640 + 4536
= 22176 cm³

Final volume of water in Tank U after 7128 cm³ of water overflowed
= 22176 - 7128
= 15048 cm³

Base area of Tank U
= 22 x 18
= 396 cm²

Height of Tank U
= 15048 ÷ 396 
= 38 cm

Answer(s): (a) 17640 cm² ; (b) 38 cm