20x + 5y is the correct answer
To do this, we're going to use the order of operations (PEMDAS):
P - Parentheses
E - Exponents
M - Multiplication
D - Division
A - Addition
S - Subtraction
First let's do parentheses, there isn't anythig in parentheses we need to simplify, so we can skip this step.
Next let's look for exponents. I see we have a
so let's replace that with
:

Now let's look for multiplcation. We know that things that are right next to eachother in parentheses represent multiplcation, so let's simply this more:



And now we're left with a simple problem we know how to solve.
Answer: 
Hope this helps!
Heya !
Given expression -

Subtracting 25 both sides ,

Dividing by 3 on both sides ,

Therefore ,
It is 9*9 21 times so
9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9=
1.09418989e20 is the answer.