Question

What is the value of x in the equation 2x + 9 = 21?
2
6
9
15

Answer 1

The answer is 6 because 2×6=12+9=21. I found my answer by first doing 2×2=4 and knowing that 4+9=13. 13 is 8 less than 21, so that is not the correct answer. Next I did 9×2=18. 18+9=27. 27 is 6 more than 21, so again that is not the correct answer. Then I did 15×2=30, I did not even have to add nine to this because it is already 9 more than 21. So, 6 is the value of x in the equation 2x+9=21.

Answer 2

2x + 9 = 21
isolate the x, do the opposite of PEMDAS, subtract 9 from both sides
2x + 9 (-9) = 21 (-9)

2x = 12
Divide 2 from both sides to isolate the x
2x/2 = 12/2
Divide
x = 12/2
Answer:
x = 6

hope this helps

In loving memory of Malkea