To answer these questions. You should know the difference between a coefficient and a variable. A coefficient is a number in front of a variable. Meanwhile a variable is a number that is represented as a letter.
a) -cd and -xy have a coefficient of -1 because if there is not number in front of the variables, we automatically assume there is a 1
b) -cd, -xy, and -3jk have two variables because in there is two letters present in each expression
c) k² has a coefficient of 1 because once again, when there is no number in front of the variable, we automatically assume there is a 1
d) 9r and 4x have one variable with an exponent of 1 because there is only one letter present in each expression and because there is no exponent displayed in these expressions, we automatically assume there is a 1
I hope I helped in some way! :)
