2.4 (c-3d)-1.3 (2c-d)
2,4(с-3д)-1.3(2с-д)= 2.4с-7.2д-2.6+1.3д=-0.2с-5.9д
2,4с-7,2d-2,6c+1,3d=-0,2c-5,9d