(2m+3n)(2m-5n),(3х+2y)(x-y),(5b-4c)(2b-2c),(p-3q)(8p+5q)

(2m+3n)(2m-5n)= 2m^2-10mn+6nm-15n^2 =
2m^2-4mn-15n^2
(3x+2y)(x-y) = 3x^2-3xy+2yx-2y^2 = 
3x^2 -xy-2y^2
(5b-4c)(2b-2c) = 10b^2-10cb+8c^2-4cb =
10b^2-14cb+8c^2
(p-3q)(8p+51) = 8p^2+51p-24pq-153q