设原来甲池蓄水x吨,则乙池蓄水(50-x)吨,则
(x-5)+3=(50-x)+3
x-5=50-x
x+x=50+5
2x=55
x=27.5
则乙池蓄水50-27.5=22.5吨.
答：原来甲池蓄水27.5吨,乙池蓄水22.5吨.