Mary had a number of cookies After eating one she gave half the remainer to her sister After eating another cookie she gave half of what was left to her brother Mary now had only five cookies left?

Answer 1

== == == == do your own math homework!!

She started with 21. Ate 1, had 20. Gave half (10) to her sister. Judy also had 10, ate one, then she had nine. Gave one-third (3) to her brother and has 6 left. ____________________

The answer provided by the person above is correct, but knowing the process to get the answer is more important. We will use simple Algebra...

Judy has a number of raisins, I am going to call this amount "X"

After eating one, she gave half the remainder to her sister...

After eating one she has "X-1" raisins of which she gave half that to her sister!

is what Judy has at this point.

After eating another raisin, she gave a third of what was left to her brother.

Eating another raisin will leave Judy with "X - 1 - (X-1)/2 - 1" of which she gave a third to her brother...

"X - 1 - (X-1)/2 - 1 - (X - 1 - (X-1)/2 - 1)/3" is how many Judy has left after giving the third to her brother!

Judy now has only six raisins left!

X - 1 - (X-1)/2 - 1 - (X - 1 - (X-1)/2 - 1)/3 = 6

Solve for X!

First, I combine the -1's to make this easier

X - 2 - (X-1)/2 - (X - 2 - (X-1)/2)/3 = 6

X -2 + -1(X-1) - (X -2 + -1(X-1)/2) = 6 is what we have because subtracting is the same as adding a negative number, and I am going to use the distributive property of equality. After simpling I am going to do the same in the parenthesis. I am going to distribute again for the second set...

X - 2 + (-X + 1)/2 + -1(X - 2 + (-X + 1)/2)/3 = 6

...

X - 2 + (-X + 1)/2 + (-X + 2 + (X-1)/2)/3 = 6 is where we are at after distributing several times.

Let's multiply each group by 3, so we can get rid of one of the fractions!

3X -6 + (-3X +3)/2 + (-X + 2 + (X-1)/2) = 18 ... Now let's get rid of the 2's by multiplying by 2

6X -12 + (-3X+3) + -2X +4 + (X-1) = 36 Nothing special anymore no need for the parenthesis

6X - 12 -3X +3 -2X +4 +X -1 = 36

Combine Like Terms

(6X -3X - 2X +X) + (-12 +3 +4 -1) = 36

(2X) + (-6) = 36

2X = 42

X = 21

As you can see, this question is really intended for you to use Algebra to solve it instead of just stabbing at it randomly. Good Luck

-Justin

Answer 2

She started with 23, then ate one and had 22. She gave 1/2 of that which is 11 to her sister. Now she has 11. She ate another one. Now she has 10! she gave 1/2 to her brother which is 5. And she was left with 5.

Answer 3

Judy had 21 raisins.

Judy has 6 raisins = 2/3 the number she had before giving 1/3 to her brother.

⇒ Judy had 6 ÷ 2/3 = 9 raisins after she had eaten 1

⇒ Judy had 9 + 1 = 10 raisins = 1/2 the number she had before giving 1/2 to her sister

⇒ Judy had 10 ÷ 1/2 = 20 raisins after she had eaten 1

⇒ Judy started with 20 + 1 = 21 raisins