How many input devices can you place in series in one rung in a relay logic diagram?

Consider a family of logic gates that operate under the static discipline with the following voltage thresholds: VI=1.5V, VOL=0.5V, VIH=3.5V, and VOH=4.4V.   a. What is the lowest voltage that can be output by an inverter for a logical 1 output? Why?   b. What is the highest voltage that must be interpreted by a receiver as logical 0? Why?   c. What is the lowest voltage that must be interpreted by a receiver as logical 1? Why?

Implement the logic circuit in Figure 2 using only NAND gate A B C X

30) Coils labeled ( S ) and ( R )A) must appear in that order (S before R) in a ladder logic programB) may be used only in subroutines in programs for Siemens PLCsC) are Short and Repeated coils, used in timing programsD) may be used instead of a seal-in arrangement to provide latching