Answer: the answer is 2m because "of" in the sentence is a multiplication key word.
Step-by-step explanation: here are some key words for all math problems like this one
Addition (+) Subtraction (-) Multiplication (× or ·) Division (÷)
sum difference product quotient
increased by decreased by times divided by
more than less than of per
more less multiplied by
added to subtracted from by
plus minus
greater than fewer than