I need help with this

5x + 2 = 12 solve the following equation. then place the correct number in the box provided.

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¯¯¯¯¯¯¯¯)?

8000 + 8800 + 8000 + 8 million + 80 trillion + another a katrillion equals