Algebraic Manipulation Given that 
$ a^2 - b^2 = 60 $ 
and
$a - b = 6 $
$a + b = 10$
Find value of $a\cdot b$
I tried 
$(a-b)^2 = 6^2 \longrightarrow a^2 - 2ab + b^2 = 36$

Hint. One may observe that
$$
2a=(a-b)+(a+b)=6+10=16
$$
$$
2b=(a+b)-(a-b)=10-6=4.
$$
