2/9*(2,7a-4,5b)-1 1/6*(2,4a+1 1/35b), если a+b= -1

2/9*(2,7a-4,5b)-1 1/6*(2,4a+1 1/35b) = 2/9*27/10a - 2/9*45/10b - 7/6*24/10a - 7/6*36/35b = 3/5a - 5/5b - 14/5a - 6/5b = -11/5a-11/5b = -11/5*(a+b)
при a+b= -1
-11/5*(-1)=11/5 =2.2