I need help, please. Please answer all!

1. 6/6 - (1/6 + 2/6)

2. 2/3 + 1/5=

3. 3/10+1/4=

4. 5/6-3/5=

5. 1/5-1/6=

Which statement best describes the polynomial

Look at attachment. has all info needed. need

Arley is building a model of a city map. in one part of the city, three roads form a right triangle, which harley draws as triangle abc, with the following measures: m∠b=90° and m∠a=30°. in his scale model, the hypotenuse of triangle abc, ac¯¯¯¯¯¯¯¯, has a length of 817−−√ cm. what is the value of a (the length of bc¯¯¯¯¯¯¯¯)?