The ratio of blue marbles to redmarbles in a bag is 11:9. If there are 99 blue marbles, in the bag, how many red marblesare there?

[latex]Radio:11:9\\ 11--99\\ \ 9--x\\ x=\frac{9}{11}*99=81[/latex]

[latex]ratio=11:9[/latex] [latex]11:9=99:x[/latex] [latex]11x=891[/latex] [latex]\frac{11x}{11}=\frac{891}{11}[/latex] [latex]x=81[/latex] There are eighty-one marbles.