Tea is made up of milk and tea ratio of 2 to 9. how much tea can be made using 1 litre of milk

You can solve it like this

2=milk (a); 1=milk (b)

9=tea (a); x = tea (b)

2:9=1:x (then multiply means and the extremes)

(means are 9 and 1; extremes are 2 and x)

9=2x

9/2 = x

4.5 or 4 1/2=x

Therefore, using 1 litre of milk, we can have 4 1/2 tea.