Question 991290
.
V_in= 120V, V_out = 18V, N_in = 180 coils, N_out = x coils.


A proportion:


{{{18/120}}} = {{{x/180}}},


The solution:


x = {{{(18*180)/120}}} = {{{(18*3)/2}}} = 9*3 = 27 coils.