Question 392227
I don't do add or subtrac both side it take to long and make confusing too, I do only one side it quick and easy, you can do both side if you want
Let x= blue , y= White
$600x+$1000y=$42000
    x+y=50
      y= 50-x
600x+1000(50-x)=42000  (subtitution y=50-x)
600x+50000-1000x =42000 (mutipy)
          -400x  =42000-50000  (simplify)
               x =-8000/-400
               x = 20
x+y+=50
20+y=50
  y = 50-20
  y = 30
Check: y=30, x=20
$600(20)+1000(30)=$12000+$30000=$42000