Нужно d : с * 100%

1.

c = 400;   d = 100

100 : 400 * 100% = 25%

2.

c = 555;   d = 111

111 : 555 * 100% = 20%

3.

c = 130;   d = 780

780 : 130 * 100% = 6 * 100% = 600%

4.

c = 321;   d = 963

963 : 321 * 100% = 3 * 100% = 300%