Question 970048
x=cc of 25% solution
   
10 cc * 0.60 (60%) + x cc * (.25) =(x+10)cc * (.30)

The right is the new solution, x of the added + 10 of what is present already.

Multiply:
6 + (0.25) x  =   .30x  + 3  ; We distribute the .30 over the (x +10)

6+ 0.25 x =0.30 x +3
Subtract 6 from each side
0.25 x =0.30 x -3

Now subtract 0.30 x from both sides
-0.05 x=-3
Multiply both sides by (-1) ; 0.05 x =3
Divide both sides by 0.05
x=0/0.05   
x=60 cc

Check
60 cc *0.25 + 10  cc *0.60=15  + 6 = 21
70 cc *0.30=21

The answer is 60 cc