Explanation 1:
Her guinea pig is
25 cm long.
25 cm = 250 mm
Her fish is 40 mm long, so her guinea pig is longer than her fish by
25 cm − 40 mm = 250 mm − 40 mm = 210 mm= 21 cm
Explanation 2:
First, lets convert the length of Naomi's guinea pig from cm to mm.
1 cm=10 mm
We can multiply each side of the equation by 25 to obtain the length of the guinea pig in mm.
25 × 1 cm = 25 × 10 mm
25 cm = 250 mm
Because we have a length of the guinea pig and the fish in a common metric we can subtract the two values: 250 mm − 40 mm = 210 mm The guinea pig is 210 millimeters longer than the fish. Or, if we want to convert this to centimeters we can divide by 10: 210 millimeters 10 = 21 centimeters
Hope this helps have a good day/night!