Factorise:

The given expression is $y^{2}+7 y-144$.

Find two numbers that follow the conditions given below:

Sum $=7$

Product $=-144$

Clearly, the numbers are 16 and $-9 .$

$y^{2}+7 y-144=y^{2}+16 y-9 y-144$

$=y(y+16)-9(y+16)$

$=(y+16)(y-9)$