For this case we can solve the problem with the following structure:
![\left|Actual-Ideal\right|\leq tolerance](https://img.qammunity.org/2023/formulas/mathematics/college/ztjx8nlcf6wxc0ar5bxfcxp81x41rdf4lx.png)
The actual weight is x
The ideal weight is 20
And the tolerance is 0.5
So then our solution would be:
![\left|x-20\right|\leq0.5](https://img.qammunity.org/2023/formulas/mathematics/college/earf9tjvrddkat7y6txkh86y3lejqa6soo.png)
And we can rewrite the algebraic model on this way:
![-0.5\leq x-20\leq0.5](https://img.qammunity.org/2023/formulas/mathematics/college/t8g3k4ln1n27eg4zu7d23px50ngmbjpip3.png)
Adding 20 in all the sides of the inequality we got:
![19.5\leq x\leq20.5](https://img.qammunity.org/2023/formulas/mathematics/college/2wblwa2ehhmncwdvenef0fygihi0wu4orq.png)