a)-28+20:(-4) ; б) 4,8×6,37+4,8×3,63

-28-5=-33
4,8*(6.37+3.63)=4.8*10=48

-28+20/(-4)= - 33
20 / (-4) = - 5
-28 + ( - 5) = - 33
4,8 × 6,37 + 4,8 × 3,63 = 48
4,8*6,37=30,576
4,8*3,63=17,424
30,576+17,424= 48