Math 好意做 快来

3.The total sales of 3 brands of ice cream are 25300.If the sales of the three brands are in the ratio of 2:4:5, find the sales of each brand.
We have
Let the three brands are A B C and the ration is 2:4:5
2k+4k+5k=25300
11k=25300
k=2300
the sales of each brand is
Brand A=2300*2=4600
Brand B=2300*4=9200
Brand C=2300*5=11500
4.In a bag, there are 110 red,green and blue balls.The number of red balls is 10 more than the number of green balls,and the number of green balls is 20 more that the number of blue balls .Findthe ratio of the number of red balls : the number of green balls : the number of blue balls.
Let the number of blue ball is x
Then the number of green ball is x+20
the number of red ball is x+20+10=x+30
So x+x+20+x+30=110
3x+50=110
x=20
Findthe ratio of the number of red balls : the number of green balls : the number of blue balls
=50:40:20
=5:4:2