Remove parentheses using "a(b+c)=ab+ac":
0.02x - (0.02)(5) + 0.06x = 6.3
0.02x - 0.1 + 0.06x = 6.3
0.08x - 0.1 = 6.3

Add 0.1 to both sides:
0.08x - 0.1 + 0.1 = 6.3 + 0.1
0.08x = 6.4

Finally, divide both sides by 0.08:

0.08x 0.08

=

6.4 0.08

x = 80