How to combine between sensors codes in Auino

Hi guys, i'm new with the Arduino program and now i'm working on my senior project. To be honest i don't know how to combine between the sensors that i used. Therefore, i searched and i found out i must add each setup together and after it did it it tells me that the interrupt setup is not declared. For now, i'm asking for combining the gas sensor (MQ-9) and the pulse sensor and here are the codes. I wish you guys help me in combining between them.

I attached for you the pulse sensor codes and it interrupt and the gas sensor codes.

PulseSensorYun.ino (4.24 KB)

Interrupt.ino (5.77 KB)

gas_sensor.ino (348 Bytes)

Please do us all a favour and read this before posting a programming question
then post your programs here including the combined program.

I wish you guys help me in combining between them.

Without knowing what the resulting program is supposed to do? That does not seem likely, does it?