Question 67415
We will let:

x=number of reds
y=number of whites
z=number of blues


Now we are told the following:
x/z=2/1 cross multiply
x=2z-------------------------our 1st equation

We are also told that:

5(x+z)=3y+12-----------------our 2nd equation

They also tell us:

y=z+4------------------------our 3rd equation

substitute x=2z into our 2nd eq. and we get

5(2z+z)=3y+12
15z=3y+12  Now substitute y=z+4 into this equation:

15z=3(z+4)+12;
15z=3z+12+12  subtract 3z from both sides and collect like terms;

12z=24
z=2 ----------------------------------number of blue balls
substitute z=2 into our 3rd eq.

y=z+4=2+4=6---------------------------number of white balls

substitute z=2 into our 1st eq

x=2z=2*2=4-----------------------------number of red balls

ck

(1)  ratio of red balls to blue balls is 2/1;  4/2=2/1 CHECKS
(2)  5 times the sum of the number of reds and blues exceeded 3 times the number of whites by 12. 5*6-12=3*6  or 18=18-------CHECKS
(3)  there were 4 more whites than blues 6-2=4   CHECKS


Hope this helps---ptaylor