Answer:
3600 ml
Explanation:
x = amount of apple juice.
amount of orange juice is 4 times apple juice = 4x
4x + x + 1800 = 6300
5x + 1800 = 6300
5x = 4500
x = 4500/5 = 900
so, there were
900 ml apple juice
4×900 = 3600 ml orange juice
1800 ml lemonade