Question

an electrician can wire a house in 12 hours. her assistant takes 18 hours to wire the same house. how long would it take them to wire the house together

Answer 1

The electrician can wire 1/12 of a house per hour.

an apprentice can do 1/18 of a house per hour.

=>x/12 + x/18 = 1

`\begin{gathered} \Rightarrow(x)/(12)+(x)/(18)=1 \\ \\ \Rightarrow(5x)/(36)=1 \\ \\ \Rightarrow x=(36)/(5)\text{ hours} \end{gathered}`

Therefore, it will take 36/5 hours to wire the house together.