6) 15 (5.4+3.5z) - 11z-6

7) 16.7x+0.5 * (-1.4x)

8) 2a (1/4-5b) + 2/3a

9) - 2.6 (5-c) - c+8

10) 2 (3x-y) - (5x-2y)

6) 15 (5.4+3.5z) - 11z-6 = 15*5,4+15*3,5z-11z-6=81+52.5z-11z-6 = (52.5z-11z) + 81-6=41.5z+75

7) 16.7x+0.5 * (-1.4x) = 16.7x-0.7x=16x

8) 2a (1/4-5b) + 2/3a=2a*1/4-2a*5b + 2/3a=1/2a-10ab+2/3a = (1/2a+2/3a) - 10ab=

7/6a - 10 b

9) - 2.6 (5-c) - c+8 = - 2.6*5 - (-2.6) * c + 8 = - 13 + 8 + 2.6c=2.6c-5

10) 2 (3x-y) - (5x-2y) = 2*3x-2y - 5x+2y=6x-5x-2y+2y=x