Question 83482
Start by finding the rate at which each person types.
If Johnathan can type the entire document in 40 minutes, then he can type 1/40 of the document in 1 minute.
If Susan can type the entire document in 30 minutes, then she can type 1/30 of the document in 1 minute.
If Jack can type the entire document in 24 minutes, then he can type 1/24 of the document in 1 minute.
Working together, they can type 1/40 + 1/30 + 1/24 of the document in 1 minute.
{{{1/40 + 1/30 + 1/24 = 3/120 + 4/120 + 5/120}}}={{{12/120 = 1/10}}}
So, together, they can type 1/10 of the document in 1 minute.
Therefore, it will take them 10 minutes to type the entire document.