Final answer:
The value of cd when c=5 and d=4 is obtained by multiplying c and d together, resulting in cd = 5 × 4, which equals 20.
Step-by-step explanation:
To find the value of cd when c=5 and d=4, we simply multiply the two numbers together. Therefore:
cd = c × d = 5 × 4 = 20
The value of cd is 20.