Question 513155
Carlos can run to ingrids house in 30 minutes.
 Ingrid can run to Carlos house in 40 minutes. 
If they start from their houses at the same time, in how many minutes will they meet?
:
Let d = the distance between the house
Let t = travel time of both when they meet
:
{{{d/30}}} + {{{d/40}}} = {{{d/t}}}
multiply by 120t, results
4dt + 3dt = 120d
7dt = 120d
divide both sides by d
7t = 120
t ={{{120/7}}}
t = 17.143 minutes travel time when they meet