Question

How do I set this up and how do I know

Answer 1

Given

Let 't' represents the time

Peg drives 30mph after he has driven 20miles, the total distance travelled here will be

`\begin{gathered} 30* t+20 \\ =30t+20 \end{gathered}`

Darren drives 45mph, hence the distance travelled will be

`45* t=45t`

Equate the two and solve for t

`\begin{gathered} 30t+20=45t \\ 20=45t-30t \\ 20=15t \\ (20)/(15)=(15t)/(15) \\ (4)/(3)=t \\ \therefore t=1(1)/(3)hr=1hr\text{ 20minutes.} \end{gathered}`

Hence, it will take 1hr 20min.