Answer:
The length of rectangle is (3a+2).
Explanation:
The area of rectangle is
.
The width of the triangle is (4a-3).
The area of a rectangle is the product of its length and width.
![A=l* w](https://img.qammunity.org/2020/formulas/mathematics/high-school/635p0kd3l22klexa3uw166lpcz3c3u5e3j.png)
![12a^2-a-6=l* (4a-3)](https://img.qammunity.org/2020/formulas/mathematics/high-school/z94tzht6ajciui4c7qarjoh4kcidqvvsq0.png)
![l=(12a^2-a-6)/(4a-3)](https://img.qammunity.org/2020/formulas/mathematics/high-school/qs5jnhhkvf4bzexf215hcutsuchbqcdpfg.png)
![l=(12a^2-9a+8a-6)/(4a-3)](https://img.qammunity.org/2020/formulas/mathematics/high-school/r8c8voxzwg28ipnul22s44lbh0ij30wavx.png)
![l=(3a(4a-3)+2(4a-3))/(4a-3)](https://img.qammunity.org/2020/formulas/mathematics/high-school/fsb8bysn0restu2szwdvcxa4wl4add8kp5.png)
![l=((4a-3)(3a+2))/(4a-3)](https://img.qammunity.org/2020/formulas/mathematics/high-school/dltarngy9ot4gjve9ynwsacixvmdgg8b6l.png)
Cancel out the common factor 4a-3.
![l=3a+2](https://img.qammunity.org/2020/formulas/mathematics/high-school/bz628fq2fbromtxf3za7z45rxk0eavh1m4.png)
Therefore the length of the rectangle is (3a+2).