I ususally use the sensible guess method too saseflower but here is another way.
What two factors of 1080 equal the sum of 69
xy=1080 (1)
x+y=69 so y=69-x (2)
sub 2 into 1
$$\\x(69-x)=1080\\
69x-x^2=1080\\
0=x^2-69x+1080\\
$now you can solve it with the quadratic formula$\\$$
$${{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{69}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1\,080}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{45}}\\
{\mathtt{x}} = {\mathtt{24}}\\
\end{array} \right\}$$
Well first guess and check
I just subtracted random numbers from 69 and then multiplyed them with the difference.
I finally got 45 and 24
Basically you just have to do guess and check
I ususally use the sensible guess method too saseflower but here is another way.
What two factors of 1080 equal the sum of 69
xy=1080 (1)
x+y=69 so y=69-x (2)
sub 2 into 1
$$\\x(69-x)=1080\\
69x-x^2=1080\\
0=x^2-69x+1080\\
$now you can solve it with the quadratic formula$\\$$
$${{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{69}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1\,080}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{45}}\\
{\mathtt{x}} = {\mathtt{24}}\\
\end{array} \right\}$$