Answer:
210 mm
Explanation:
We need to work with the same units, so we need to convert cm to mm
1 cm = 10 mm
So 25 cm * 10 mm/ 1 cm = 250 mm
The guinea pig is 250 mm
Subtract the fish's length from the guinea pigs length to see how much longer the guinea pig is
guinea pig - fish
250 mm - 40 mm
210 mm