5x(5x3+9^2)+4

I got 28x^2+88
I know i wrong but idont know how to do the problem.
There isn't a value for x, it's an unknown variable.

OK. what does 5x3 mean?

using the distributive law, we have

(5x)(5x3) + (5x)(9^2) + 4

Now, how you get from there to 28x^2+88 is beyond me.