If the math adds up the submarine will travel .6 km in .25 hours.
THE ANSWER WILL BE 3 BECAUSE I HAD DID MY MATH
So, let's make these two values improper fractions so they're easier to work with. 
So, to get the rate he grew in those months we have:
And to get the rate he grew in one month we have to divide both our numerator and our denominator by 21 to get:
aka he grew 1.24 inches in a month.
the distance formula to find the length of the sides... opposite sides equal it could be a rectangle or parallelogram all sides equal, square or rhombus adjacent equal, kite and then the slope is used to check angles if the product of the 2 lines in -1 the lines are perpendicular (right angle) the the slopes of 2 lines are the same the sides are parallel.
I think this is it ^_^
