For this case the first thing you should know is the following conversion:
![1 minute = 60 seconds](https://img.qammunity.org/2019/formulas/mathematics/college/ikbnt4r3lzup08xbbaodf3v7mbu3e160rz.png)
We can then make the following rule of three:
1 minute ----------> 60 seconds
3/4 minutes -------> x
From here, we clear the value of x.
We have then:
Answer:
there are 45 senconds in 3/4 of a minute