Answer:
![21.43\%](https://img.qammunity.org/2021/formulas/mathematics/middle-school/6mxau1twsjh06j1blf0g5sezq0lsho09g1.png)
Explanation:
we know that
To find out the percent of robots which are defective, divided the number of defective robots by the total number of robots and multiply the result by 100
Let
x ----> the number of defective robots
y ----> the total number of robots
p ---> percentage of robots which are defective
so
![p=(x)/(y) (100)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/5nar6b1eoffx4rdzav94j75gb53tj7deks.png)
we have
![x=30\\y=140](https://img.qammunity.org/2021/formulas/mathematics/middle-school/4mrxw8hk6zyjzefxdk10obxe0qjmzy0vob.png)
substitute
![p=(30)/(140)(100)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/z938nfpvlekh1ev1dnzjbsba714mgsw035.png)
![p=21.43\%](https://img.qammunity.org/2021/formulas/mathematics/middle-school/i1n3lrc35umupty0v4znfirsb8f78c3yel.png)