4.3b-(7.8b-3)-4.1
при b= -1.2

4.3*(-1.2)-((7.8*(-1.2)-3)-4.1=-5.16-(-9.36-3)-4.1=-5.16-(-12.36)-4.1=-5.16+12.36-4.1=7.2-4.1=3.1