Answer:
volume of old tank=20×4×10=800m³
no of shark adjust =800/25=32 sharks is adjusted in old shark tank
for new
if length=25℅0f 20+20=25m
breadth=25%of 4 +4=1+4=5m
height is same=10m
new volume =25×5×10=1250m³
total no.of shark adjust=1250/25=50 shark
50-32=18 more shark that the new tank hold.