find the values of V3 and V4....

voltage is given across the elements with polarities right.

if all the elements voltages are known around the loop then, kvl can be applied this way.

start from one point and go in any direction. while crossing the element write the element potential with polarity that is present on the other side of the element. write the same for all elements. if all elements are over and loop is completed then put that equation equal to zero. write equation for every loop and solve the linear equations.