Answer:
To do this you have to use ratios and proportions
as you know the water and screenwash ratio in winter is
1/5
so when you are taking 150 ml of screenwash you need 150 *5 ml of water as the ratio will be the same so
the water will be 2250ml
and in summer the ratio is 1 / 10
which will give a screenwash in ml would be 450 /10 = 45
here is the answer