Can somebody please tell me the answer of this?

X+ y = 5 ; x - y =3 solve using linear combination

Convert the mixed numbers into improper fractions. convert the improper fraction to mixed numbers.

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?