Answer :
Call the amount of pineapple "P', and the amount of gingerale "G".
We know that a mix of pineapple and gingerale makes 200 cups. So:
[tex] P+G=200 [/tex]
We also know that double the pineapple (i.e. 2P) and triple the gingerale (i.e. 3G) makes 420 cups. So:
[tex] 2P+3G=420[/tex]
We can now solve by substitution:
[tex] 2P+3(200-P)=420[/tex]
[tex]2P+600-3P=420[/tex]
[tex]-P=-180[/tex]
[tex]P=180[/tex]
[tex]180+G=200[/tex]
[tex]G=20[/tex]
For 420 cups we need 2P=360 cups of pineapple and 3G=60 cups of gingerale]
We know that a mix of pineapple and gingerale makes 200 cups. So:
[tex] P+G=200 [/tex]
We also know that double the pineapple (i.e. 2P) and triple the gingerale (i.e. 3G) makes 420 cups. So:
[tex] 2P+3G=420[/tex]
We can now solve by substitution:
[tex] 2P+3(200-P)=420[/tex]
[tex]2P+600-3P=420[/tex]
[tex]-P=-180[/tex]
[tex]P=180[/tex]
[tex]180+G=200[/tex]
[tex]G=20[/tex]
For 420 cups we need 2P=360 cups of pineapple and 3G=60 cups of gingerale]