Answer:
1) 18 Quart of Sparkling water need to mix with 9 quart grape juice
2) 15/2  Quart of grape juice required for 15/4 quarts of sparkling water.
3) Quantity of grape juice  and  sparkling water in 100 quart of punch are 33 1/3 quart  and 66 2/3 quart respectively.
Step-by-step explanation:
1 1/2 quarts = 1 + (1/2) = 3/2 quarts
1)  water required for 3/4 quart of grape juice =  3/2 quarts
so water required for 1 quart of grape juice = (3/2) ÷ (3/4) = (3/2)× (4/3) = 2 quarts
so water required for 9 quart of grape juice = 9 * 2 = 18 quart
18 Quart of Sparkling water need to mix with 9 quart grape juice
2) From solution of 1 , 
    For 18 quart of Sparkling water , grape juice require = 9 quart 
    So for 1 quart of Sparkling water , grape juice require = 9÷18 = 1/2 Quart
    so for 15/4 quart of Sparkling water ,  grape juice require = 1/2 × 15/4 =
 15/2  Quart of grape juice required for 15/4 quarts of sparkling water.
3) 
in 1 we calculated that 18 Quart of Sparkling water need to mix with 9 quart grape juice that is 2 quart of Sparkling water need to mix with 1 quart of grape juice.
In other words 1 quart of grape juice + 2 quart of sparkling water is 3 quart of punch.
Quantity of Grape juice in 3 quart of punch = 1 quart
so quantity of grape juice in 1 quart of punch = 1/3 quart
And quantity of grape juice in 100 quart of punch = 100×(1/3) = 100/3 = 
33 1/3
Quantity of sparkling water in 3 quart of punch = 2 quart
so quantity of sparkling water  in 1 quart of punch = 2/3 quart
And quantity of sparkling water  in 100 quart of punch = 100 ×2/3 quart = 66 2/3