5. Упростите выражение: 2/7(1,4a - 3 1/2 b) - 1,2(5/6 a - 0,5b)

Distribute the coefficients: (2/7 * 1.4a) - (2/7 * 3.5b) - (1.2 * 5/6 a) + (1.2 * 0.5b)
= 0.4a - b - a + 0.6b
Combine like terms: (0.4a - a) + (-b + 0.6b) = -0.6a - 0.4b