4) 16x - x + 14 = 299; 5) 7b +66-29 = 374;

Определим предмет: математика.

1. 16x - x + 14 = 299 $$15x = 299 - 14$$ $$15x = 285$$ $$x = rac{285}{15}$$ $$x = 19$$
2. 7b + 66 - 29 = 374 $$7b + 37 = 374$$ $$7b = 374 - 37$$ $$7b = 337$$ $$b = rac{337}{7} = 48rac{1}{7}$$

Ответ:

1. x = 19
2. $$b = 48rac{1}{7}$$