1276
1)0,3х+0,8у+1,5х+1,2у= (0,3x+1,5x)+(0,8y+1,2y)= 1,8х+2у
2)4,2х+5,3у-2,6у-1,8х= (4,2x+(-1,8x))+(5,3y-2,6y)= 2,4х+2,7у
3)1,5а+9,7b+5,8a-1,3b= (1,5a+5,8a)+(9,7b+(-1,3b))= 7,3a+8,4b
4)12,75a+1,85b-9,55a+3,5b= (12,75a+(-9,55a))+(1,85b+3,5b= 3,2a+4,90b