Answer
$a^2-1.3a+0.42$
Work Step by Step
Using $(a+b)(c+d)=ac+ad+bc+bd$ or the product of $2$ binomials, the given expression, $
(a-0.6)(a-0.7)
$, is equivalent to
\begin{array}{l}\require{cancel}
a(a)+a(-0.7)-0.6(a)-0.6(-0.7)
\\\\=
a^2-0.7a-0.6a+0.42
\\\\=
a^2-1.3a+0.42
.\end{array}
