This might be a trick question. I did the problem and got the exact same answer. I got 31 x + 0.5. If there's anything they did wrong maybe its because they didn't put a zero before 5 so 5 could become a decimal?
Answer:

Step-by-step explanation:

Let's solve:

4(
)
x = 16
Let's check:


4 = 4
Hope this helps!
The correct answer is b.24
Answer is Mary because
8/8 is a whole
4/8 is a half
3/8 is less than 1/2