Math
posted by Marie on .
The electric current I in a circuit varies directly as the voltage V. When 21V are applied, the current is 4A. What is the current when 18 volts are applied

i = k V
4 = k (21)
k = 4/21
i = (4/21) 18 = 4*6/7 = 24/7 = 3.43 amps