IP-:$210.15.131.141$
Mask-:$255.255.255.224$
$\Rightarrow$Seeing the IP we can guess that it is class C$\Rightarrow$Network bit=24 bit and host=8 bit
$\Rightarrow$Its mask must be $11111111.11111111.11111111.00000000$ but it is actually $11111111.11111111.11111111.11100000$$\Rightarrow 3$ bit is taken away from host $\Rightarrow$3 bit must be its subnet
$\Rightarrow$ subnet bits are $000$,$001$,$010$,$011$,$100$,$101$,$110$,$111$
$\Rightarrow$ ANDing IP with mask we get Network address of that IP
$11010010.00001111.10000011.10001101$
AND
$11111111.11111111.11111111.11100000$
$11010010.00001111.10000011.10000000$
Also,last subnet is $111$
So Finally addrress of last host of last subnet is $11010010.00001111.10000011.10000000.111111110$
210.15.131.254