(-1,2a+2,5в)*4+3(3,2a-0,6в)=
(-1,2а+2,5в)*4+3(3,2а-0,6в)= -4,8а+10в+9,6а-1,8в= (9,6-4,8)а+(10-1,8)в=4,8а+8,2в.