9. Surveying From the top of a canyon, the angle of depression to the far side of the river is 58°, and the
angle of depression to the near side of the river is 74º.
The depth of the canyon is 191 m. What is the width
of the river at the bottom of the canyon? Round to
the nearest tenth of a meter.

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?