Ms. Jan brought in cookies for her class. She gave out half of them in the morning. At lunch, she gave out 12 more. She then had 10 cookies left. How many cookies did she bring in?

2 Answers
Aug 17, 2016

Ms. Jan brought 44 cookies.

Explanation:

In order to solve this problem, we need to work backwards. First, we have 10 cookies left at the end of the day. At lunch, she gave away 12 cookies. This means that Ms. Jan had 22 cookies at lunch since #10+12=22#.

In the morning, Ms. Jan gave out half of her cookies. This means that she started with twice as many cookies as she had at the beginning of lunch. #22*2=44#. Therefore, Ms. Jan brought 44 cookies.

Aug 17, 2016

44 cookies.

Explanation:

We can work out the number of cookies by forming an equation and solving it.

Let the original number of cookies be #x#.

Thinking through the process we have:

#x div 2 rarr "subtract " 12 rarr 10 " left"#

#x/2 -12 = 10#

#x/2 = 10+12#

#x/2 = 22 " 22 is half of the number"#

#x =2xx 22 =44#