Решить выражения 1) 3,9а-2,81b-5,1а+4,9b 2)1 3/4x-3 7/11у+2 1/4х-5 4/11y 3)-1 5/12m-5/7n-7/12m-2/7n

1) 3,9а-2,81b-5,1а+4,9b = -1,2а +2,09в

2)1 3/4x-3 7/11у+2 1/4х-5 4/11y = 7/4х+9/4х-40/11у-59/11у=16/4х-99/11у=4х-9у

3)-1 5/12m-5/7n-7/12m-2/7n= - 17/12m-7/12m-5/7n-2/7n= - 24/12m-7/7n= - 2m-n