This sum is an example of internal transfer. When there is internal transfer, total REMAINS THE SAME. So your before ratio is 3:5 and after ratio is 4:5. Total before is 8 units and total after is 9. Make them the same into 72 units. Multiply 3:5 by 9 thruout and multiply 4:5 by 8 thruout. New b4 ratio is 27:45 and new after ratio is 32:40.
5 units= 2500 g
1 unit= 500g
72 units= 500 x 72= 36000 g