a) What is the formal description of Set A?

A={x∣x∈N and x<20}
A={x∣x∈P and 30A={5x∣x∈Z and x is even}

b) What is the formal description of Set B?

B={x∣x∈N and x<20}
B={x∣x∈P and 30B={5x∣x∈Z and x is even}

c) What is the formal description of Set C?

C={x∣x∈N and x<20}
C={x∣x∈P and 30C={5x∣x∈Z and x is even}