(3x)^3

(power of a product rule)

Step-by-step explanation:

Here is your workings

(3x)^3  Apply the rule of exponents

Step 2

(3x)^3=3^3x^3  Simplify

Step 3

3^2=27  Solve

27x^3

i will explain a general approach for repeating numbers.

say x = 0. (repeating).

then multiply by 10³=1000 since we have 3 repeating digits, and subtract the original:

1000x-x = 135. - 0. = 135

now we have an equation that we can solve for x.

1000x - x = 135 => 999x = 135 => x = 135/999

with this approach you can calculate all repeating numbers as fractions.