This is a pond in the shape of a prism. it is completely full of water. colin uses a pump to empty the pond. the level goes down by 20cm in the first 30 minutes. work out how many minutes colin has to wait for the pond to completely empty.

Type the correct answer in the box. consider the system of linear equations below. rewrite one of the two equations above in the form ax + by = c, where a, b, and c are constants, so that the sum of the new equation and the unchanged equation from the original system results in an equation in one variable.