Question

Cindy was asked by her teacher to subtract 2 from a certain number and then divide the result by 4. Instead, she subtracted 4 and then divided the result by 2, giving an answer of 31. What would her answer have been if she had worked the problem correctly?

A) 15
B) 17
C) 19
D) 21

Answer 1

If Cindy had worked the problem correctly, her answer would have been 33.

Step-by-step explanation:

To solve this problem, we need to understand the correct order of operations. The correct order is to subtract 2 from the number first, and then divide the result by 4. Let's say the number is 'x':

Correct calculation:
x - 2 ÷ 4 = x - 0.5

Now, since Cindy subtracted 4 instead of 2, we can set up the equation:

x - 4 ÷ 2 = 31

To solve this equation, we first need to undo the division. Multiplying both sides by 2 gives us:

2(x - 4 ÷ 2) = 2(31)

Which simplifies to:

2x - 4 = 62

Adding 4 to both sides gives:

2x = 66

Dividing both sides by 2 gives the final answer:

x = 33

Therefore, if Cindy had worked the problem correctly, her answer would have been 33. Answer choice D, 21, is not correct.