The formula for the area of a triangle is:
![Area=(1)/(2)(base* height)](https://img.qammunity.org/2023/formulas/mathematics/college/jp620t9iq0tinmphcsmym5yxengswcs6mp.png)
The height of this triangle is 7in, the area is equal to 84 squared inches, and the base is represented as x. Substitute those values on the formula:
![84=(1)/(2)(7x)](https://img.qammunity.org/2023/formulas/mathematics/college/d56x5rgmity05251io16xoufc34erlx21u.png)
Multiply both sides by 2 and divide by 7 to isolate x:
![\begin{gathered} x=(2)/(7)*84 \\ =(168)/(7) \\ =24 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ndzf70ggo354z4ile68nzbqxhxxkcjgcpy.png)
Therefore, the value of x is 24 in.