What to do with the exponent

(3x)²(5y)=

This is beyond me and how can this be applied in a life situation?

as stated: (3x)² (5y) = (9x²)(5y) = 45x²y

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if the exponent were on the inside of the parentheses with the 3x:

(3x²) (5y) = (3x²)(5y) = 15x²y

the parentheses decide the scope of the exponent applied.

When exponents are outside the parenthesis, you must distribute the exponent to the monomial term's factors. In this case, these factors are 3 and x. 3 and x both have an exponent of 1, so
(3^1(2))(x^1(2))(5y) =
(3^2)(x^2)(5y) =
(9x^2)(5y) =
45yx^2

Oh, and from here on out, it's kind of not entirely used in everyday life. But the application deals with exponentially growing bacteria and other stuff like that.

Forget the life situation -----just do the question.

(3x)² (5y) = (9x²)(5y) = 45x²y

Believe me , all over the world , Algebra is used in real life situations.