(4625:b+1995):1000+98=400-300
(4625:b+1995):1000+98=100/-98
(4625:b+1995):1000=2
(4625:b+1995)=2×1000
(4625:b+1995)=2000
4625:b=2000-1995
4625:b=5
b=4625:5
b=925
