4(b+0.8)+1.7b = 4*b+4*0,8+1,7*b = 5,7*b+3,2 = 5,7*2,3+3,2=(57/10)*(23/10) + 32/10 =

= (57*23)/(10*10) + (32*10)/(10*10) = 1311/100 + 320/100 = 1631/100=16,31.