3c-2d=2
3c+4d=30
solve each system of equations by using elimination

3c - 2d = 2  / × ( - 1 ) ;
You obtain -3c + 2d = - 2 ;
           But, +3c + 4d = 30 ;
                 (+)
                     /       6d = 28 ;
                             d = 28 / 6 = 14 / 3 ;
Finally, 3c - 2 * ( 14 /3 ) = 2 ;
             3c - 28 / 3 = 2 ;
             9c / 3 - 28 / 3 = 6 / 3 ;
             9c - 28 = 6 ;
             9c = 6 + 28 ;
             9c = 34 ;
             c = 34 / 9 ; 

This water melon must be sweet.
Since we are told  that it is 95% water.
The % not water = (100-95)% = 5%.

= 5% of 20 lbs.

= 5/100 * 20 = 1 lb.

Therefore 1 lb of it is not water. Delicious.