To solve this equation, first simplify the left side:

(7/8 - 0.2) * x = 8.1

(7/8 - 2/10) * x = 8.1

(35/40 - 16/80) * x = 8.1

(35/40 - 2/10) * x = 8.1

(9/40) * x = 8.1

Now multiply both sides by 40/9 to solve for x:

x = 8.1 * (40/9)

x = 36

Therefore, the value of x is 36.