Выражения : 1) 8,4-2,7(7b-1.3(10-.7b 2) 15.1c+0.9(4c-2.8(1.4+0. help me!

1) 8,4-2,7(7b-1,3(10-11b))-15,7b = 8,4-2,7(7b-13+14,3b)-15,7b=8,4-18,9b+35,1-38,61b-15,7b=43.5-73,21b
2) 15.1c+0.9(4c-2.8(1.4+0.2))-20c=15.1c+0.9(4c-3.92-0.56)-20c=15.1c+3.6c-3.528-0.504-20c=-1.3c-4.032