6 2/5 + 2 3/4 + 2 1/3

Given this information, which expression must represent the value of b?

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¯¯¯¯¯¯¯¯)?

Which equation is y = -6x2 + 3x + 2 rewritten in vertex form?