To multiply (2x-9y)·(5x+y), we use the distributive property:

= 2x(5x) + 2x(y) - 9y(5x) - 9y(y)
= 10x^2 + 2xy - 45x - 9y^2

Now, to multiply -10·(x+2)², we use the distributive property:

= -10·(x^2 + 4x + 4)
= -10x^2 - 40x - 40

Putting it all together:

(2x-9y)·(5x+y) - 10·(x+2)²
= 10x^2 + 2xy - 45x - 9y^2 - 10x^2 - 40x - 40
= 2xy - 85x - 9y^2 - 40