Which of the following are not correct expressions for slope

Can someone me and plz do the problem

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?