2(a-3b)+3a+b,esli a-b=4 uprastite virajenye i naydyte ego znachenie
2(a-3b)+3a+b = 2a - 6b + 3a + b = 5a - 5b = 5(a-b).
Т.к. a-b = 4, то 5(a-b) = 5*4 = 20