For the given part of circuit calculate potential `V_(p)` of centre point P and then find current `I_(1)`.

Explanation

Let potential of point P is `V_(P)`. By using KCL at point `PI_(1)+I_(2)+I_(3)=0` so `(V_(p)-6)/(20)+(V_(p)-10)/(10)+(V_(p)-5)/(30)=0`
`rArr 3(V_(p)-6)+6(V_(p)-10)+2(V_(p)-5)=0rArr11V_(p)-88=0rArrV_(p)=8` volt
an d current `I_(1)=(8-6)/(20)=0.1A`