With 21 V applied, if R_{1} = 5 ohms, R_{2} = 35 ohms, and R_{3} = 14 ohms, what is the current of R_{2} if R_{1} is series connected with parallel circuit R_{2} and R_{3}?

What is the total resistance of a circuit when R_{1} (7 k ) is in series with a parallel combination of R_{2} (20 k ), R_{3} (36 k ), and R_{4} (45 k )?