# Three Variable Simultaneous Differential Equation

## Main Question or Discussion Point

I have had a troubling time trying to solve this equation out of this book I have (not homework, just for fun). Here it is:

dx/(y+z)=dy/(x+z)=dz/(x+y)

I've tried the substitution u=x+y+z, du=dx+dy+dz but I couldn't arrive at an answer. Any suggestions?