To determine how many people are needed for a project, an architect uses the function f(x)=( 3x^2+13x)/(x+1), where x is the number of people and f(x) is the number of hours. If the architect knows the project will take at least 20 hours, what is the minimum number of people needed?

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?