Re: bag of marbles question 5th grade HELP!

Consider:

R= number of red marbles

B= number of black marbles

B = R + 18

0.45(B + R) = R



0.45(R + 18 + R) = R

0.45(2R + 18) = R

0.90R + 8.1 = R

8.1 = 0.10R

81 = R

B = 81 + 18 = 99



"Marvel" <goh@[EMAIL PROTECTED]
> wrote in message 
news:42244$47fad5af$45283fd7$2586@[EMAIL PROTECTED]
> What would the formula be?
>
> In a bag of  red and black marbles there are 18 fewer red marbles than 
> black
>
> If 45% of the marbles are red how many marbles are in the bag.
>