Two fractions that lie between 2/5 and 4/5

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?

Solve the formula ax+ by = c for x.

Find the distance between the pair of points a(-1,8) and b(-8,4)