Question

Tank B, which initially contained 80 liters of water, is being drained at a rate of 2.5 liters per minute. For how many minutes has the water been draining when Tank B contains x liters of water (answer as an expression)?

Answer 1

x=water in the tank in liters

t=time in minutes

start by writing the expression of the draining in the tank

`x=80-2.5t`

being 80 the initial value and 2.5 the rate at which is draining

to see how many minutes the tank has been draining when containing x liters clear the equation for t

`\begin{gathered} x=80-2.5t \\ x-80=-2.5t \\ 2.5t=80-x \\ t=(80-x)/(2.5) \\ t=(80)/(2.5)-(x)/(2.5) \\ t=32-(x)/(2.5) \end{gathered}`