Chapter 6.5, Problem 15P

Tran write following word problem for $1\frac{3}{4}÷\frac{1}{2}?:$

There are $1\frac{3}{4}$ pizzas left. Tran eats half of the pizza that is left. How many pieces of pizza did Tran eat?
Tran shown the diagrams in Figure 6.29, saying that they show that

Figure 6.29 Why is this not a word problem for $1\frac{3}{4}÷\frac{1}{2}?$

$1\frac{3}{4}÷\frac{1}{2}=3\frac{1}{2}$

a. Even though Tran gets the correct answer to the division problem, explain why his problem is not a correct word problem for $1\frac{3}{4}÷\frac{1}{2}?.$

b. Write a correct word problem for $1\frac{3}{4}÷\frac{1}{2}?$ that is about $1\frac{3}{4}$ pizzas.