A 1.0 kg mass changes speed from 2.0 m/s to 11.0 m/s. What is the
mass's change in momentum?

the entire statement is true and correct.  

there's no diagram, nothing is illustrated, and no question is asked.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

because if the tool that you are using is not balanced it there would be false mass.

answer///terminator or twilight zone;