Help plz

Simplify.7x + 3y - 2 + 6x + 1 + y squared 2 you! ; )

Find the missing dimension extra points

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?