упростите выражение-умножение многочлен на многочлен

-5x(x-2)+(x-3)(5x+1)= -5x+10x+5x+x-15x-3= 10x+x-15x-3= -4x-3.
3a(a-b)-(a+b)(3a-b)= 3a-3ab-(3a-ab+3ab-b)= 3a-3ab-(3a+2ab-b)= 3a-3ab-3a-2ab+b= -3ab-2ab+b = -5ab+b.
(2a-b)(3a+b)+(3a-5b)(a-b)= 6a+2ab-3ab-b+3a-3ab-5ab+5b= 9a-9ab+4b.
(5xy-y)(x-2y)-(x+2y)(5x-3y)= 5xy-10xy-xy+2y-(5x-3xy+10xy-6y)= 5xy-10xy-xy+2y-5x+3xy-10xy+6y= 5xy-10xy-11xy+8y-5x+3xy.
3a(a+3)+(2-a)(3a-4)= 3a+9a+6a+8+3a+4a= 9a+6a-8+4a= 19a-8.
7x(x-2y)-(x-y)(7x+y)=7x-14xy-(7x+xy-7xy-y)= 7x-14xy-(7x-6xy-y)= 7x-14xy-7x+6xy+y= -14xy+6xy+y= -8xy+y.
(3m-2n)(2m-3n)+(3n-m)(2n-m)= 6m-9mn+4mn+6n+6n-3mn-2mn+m= 7m-18mn+12n.
(2a-5b)(a+b)-(b-2a)(a-5b)= 2a+2ab-5ab-5b-(ab-5b-2a+10ab)= 2a+2ab-5ab-5b-ab+5b+2a-10ab= 4a-8ab-6ab.