0.2 (d-6) = 0.3d+5-3+0.1d

First distribute

a (b+c) = ab+ac

0.2 (d-6) = 0.2d-1.2

now we have

0.2d-1.2=0.3d+5-3+0.1d

gropu like terms

0.2d-1.2=0.3d+0.1d+5-3

add like terms

0.2d-1.2=0.4d+2

subtract 0.2d from both sides

-1.2=0.2d+2

subtract 2 from both sides

-3.2=0.2d

divide both sides y 0.2

-16=d