What is the total number of gates required to build a 4-bit adder? Assuming two transistors per

Question:

What is the total number of gates required to build a 4-bit adder? Assuming two transistors per NOT gate (as in Figure 16.8) and four transistors per AND and OR gate (as in Figures 16.9 and 16.10, respectively), what is the total number of transistors in the circuitry of the 4-bit adder?