y=3(x+5)(x-2)

I'm suppose to simplify right?
There is no way to solve for the variables.

y=3(x+5)(x-2)
use the distributive property
y=3x+15(x-2)
y=3x+15x-30
y=18x-30

thanks for your help but the book says the answer is y =3xsquared + 9x-30

how did they get answer?

To simplify the expression, we can apply the distributive property multiple times. Let's go through the steps again:

Starting with the expression y=3(x+5)(x-2), we can start by distributing the 3 to both terms inside the parentheses:

y = 3 * (x + 5) * (x - 2)
= 3 * (x * (x - 2) + 5 * (x - 2))

Next, we can apply the distributive property again to both terms inside the parentheses:

y = 3 * (x * x - 2 * x + 5 * x - 2 * 5)
= 3 * (x^2 - 2x + 5x - 10)

Simplifying further, we can combine like terms:

y = 3 * (x^2 + 3x - 10)
= 3x^2 + 9x - 30

Therefore, the simplified form of the expression y=3(x+5)(x-2) is y=3x^2 + 9x - 30.

It's possible that there was an error in the book or a misinterpretation. The answer you obtained, y=18x-30, is not equivalent to y=3x^2 + 9x - 30. Double-checking the steps above, the latter is the correct simplified form.