Question 95147
Let x=number of reds
And y=number of blues
Now we are told that:

0.10x+0.20y=24-----------------------------eq1

We are also told that:
x*3=y+20 or

3x=y+20 subtract 20 from both sides
y=3x-20  -----------------------------------eq2

substitute y=3x-20 from eq2 into eq1

0.10x+0.20(3x-20)=24  get rid of parens

0.10x+0.60x-4=24   add 4 to both sides

0.10x+0.60x-4+4=24+4  collect like terms

0.70x=28  divide both sides by 0.70
x=40---------------------------------------number of reds

substitute x=40 into eq2:

y=3*40-20
y=120-20=100-------------------------------number of blue

CK

0.10*40+0.20*100=24
4+20=24
24=24
also

3*40 exceeds 100 by 20


Hope this helps--ptaylor