№1. Решите уравнения.

a) \( \frac{1}{6}x = 18 \): \( x = 18 \cdot 6 \): \( x = 108 \). b) \( 7x + 11.9 = 0 \): \( 7x = -11.9 \): \( x = -\frac{11.9}{7} \approx -1.7 \). c) \( 6x - 0.8 = 3x + 2.2 \): \( 6x - 3x = 2.2 + 0.8 \): \( 3x = 3 \): \( x = 1 \). d) \( 5x - (7x + 7) = 9 \): \( 5x - 7x - 7 = 9 \): \( -2x - 7 = 9 \): \( -2x = 16 \): \( x = -8 \).