Упростите выражение: 56 6+6 90 1) b-3-26-6 b²+6b

1) \[\frac{5b}{b-3} - \frac{6+b}{2b-6} \cdot \frac{90}{b^2+6b}\] \[\frac{5b}{b-3} - \frac{6+b}{2(b-3)} \cdot \frac{90}{b(b+6)} = \frac{5b}{b-3} - \frac{(6+b) \cdot 90}{2(b-3) \cdot b(b+6)} = \frac{5b}{b-3} - \frac{90}{2b(b-3)} = \frac{5b}{b-3} - \frac{45}{b(b-3)} = \frac{5b^2 - 45}{b(b-3)} = \frac{5(b^2 - 9)}{b(b-3)} = \frac{5(b-3)(b+3)}{b(b-3)} = \frac{5(b+3)}{b}\]