a)
If he could use all the lemonade he would need 200 ( 5/3) = 333.33 ml of lme juice....not enough lime juice for this
If he could use all the lime juice.....he would need 300 (3/5) = 180 ml of lemonade.....enough lemonade for this
So.....the amount of fizzy drink he could make = 300 + 180 = 480ml
b ) If he could use all the lemonade he would need 190 ( 5/3) = 316.66 ml of lme juice....not enough lime juice for this
If he could use all the lime juice.....he would need 300 (3/5) = 180 ml of lemonade.....enough lemonade for this
This will not affect the amount he can make