For this case we can set uo an equation given by:
![y=10x+20](https://img.qammunity.org/2023/formulas/mathematics/high-school/7hlg1vnv7xqi3kzhel5dxrbxjafyqd8mjx.png)
Where y represent the final cost. x the number of Gig used and for this case we can set up the following equation:
![60=10x+20](https://img.qammunity.org/2023/formulas/mathematics/college/h3x9e5o8s1k9a0fee3sly6ii5n0tjh6rss.png)
And solving for x we got:
![x=(60-20)/(10)=(40)/(10)=4](https://img.qammunity.org/2023/formulas/mathematics/college/1ad1duaxh40s8vn28sqrd9599phpr99awd.png)
And the final answer for this case woudl be 4 Gig of data used