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Andrew is trying to create a number puzzle for his younger sister to solve. He challenges his sister to find the mystery number. “When 4 is subtracted from half of a number the result is 5.” The equation to represent the mystery number is 1/2−4=5.
Andrew’s sister tries to guess the mystery number.

a. Her first guess is 30. Is she correct? Why or why not?


b. Her second guess is 2. Is she correct? Why or why not?
c. Her final guess is 4 1/ 2. Is she correct? Why or why not?

Respuesta :

mackenzierreed

Answer:

a. she is not correct. half of 30 is 15 and 15 - 4 is 11.

b. she is not correct. half of 2 is 1 and 1 - 4 = -3.

c. she is not correct. half of 4 1/2 is 2 1/4 and 2 1/4 - 4 = -1 3/4.

the correct answer is 18. half of 18 is 9, and 9 - 4 = 5.

emeldrum587

None of these guesses are correct.

Let's work this problem in reverse.

Try it this way.

1/2x-4=5

This is actually quite simple to solve.

Because half of x minus 4 will equal 5, we just need to add 4 and 5 to get half of our mystery number. 4+5=9. So, 9 is half of x. Add 9 to 9 to get our mystery number, which is 18.

30 is not correct because Half of 30 is 15, and 15-4 is 11, not 5.

2 is also not correct because half of 2 is one, and 1-4 is -3, not 5.

4 1/2 is not correct as well because half of 4 1/2 is 2 1/4, and 2 1/4-4 is -2 1/2, not 5.

Hope this helped!

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