Which are correct please help​

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

What is the volume of this container?

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?