Chapter 4 - Polynomials - 4.7 Polynomials in Several Variables - 4.7 Exercise Set - Page 284: 55

$30x^2-28xy+6y^2$

Using $(a+b)(c+d)=ac+ad+bc+bd$ or the product of $2$ binomials, the given expression, $ (6x-2y)(5x-3y) ,$ simplifies to \begin{array}{l}\require{cancel} 6x(5x)+6x(-3y)-2y(5x)-2y(-3y) \\\\= 30x^2-18xy-10xy+6y^2 \\\\= 30x^2-28xy+6y^2 .\end{array}