Each number in the ratio 4:5:7 is worth 6 sweets. add 4,5, and 7 to get 16 then multiply it by 6 to get 96 sweets.
Your sister and you drank 550 milliliters all together.
A+B = 2X -2
A-B = 4X -8
Add the equations,
2A = 6X - 10
A = 3X - 5
Now, 3X - 5 + B = 2X - 2
B = 2X-3X - 2 + 5
B = 3 - X
Hope this helps!
