Answer:
The mechanical age can be defined as the time between 1450 and 1840. A lot of new technologies were developed in this era due to an explosion of interest in computation and information. Technologies like the slide ruler (an analog computer used for multiplying and dividing) were invented in this period.
R₂ and R₃ can be replaced by:

The total R of the circuit is R₁+R₅+R₄ = 706 2/3
So the current in the circuit I=V/R is 100/(706 2/3) = 15/106 A
(I'm deliberately not trying to round the result)
The voltage drop over R₄ is V=I*R = 15/106 * 500 ≈ 70
So answer C would be my choice.
The answer is a) <span>so you can provide enough time studying. </span>