Brad and Terrence are working on some math problems. Today, Terrence completed 15 math problems. This is 3 more than twice the number of problems that Brad completed. A)Write an equation that can used to find , b, the number of math problems that Brad completed.​

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¯¯¯¯¯¯¯¯)?