Consider the rectangle drawn below,
Consider the properties of rectangle that the opposite sides are equal, and both the diagonals are also equal in length.
![QS=RT\Rightarrow3x+7=5x-3\Rightarrow5x-3x=7+3\Rightarrow2x=10\Rightarrow x=5](https://img.qammunity.org/2023/formulas/mathematics/college/5n3hcsgtnm9m4gfi0xrakyo9ykgdrmrzxj.png)
Thus, the value of 'x' is 5.
Substitute the value to obtain the diagonal QS as,
![QS=3(5)+7=15+7=22](https://img.qammunity.org/2023/formulas/mathematics/college/epw3b8vv2j5o3pmxvwbcmxk1ortjng0ha1.png)
Similarly solve for the diagonal RT as,
![RT=5(5)-3=25-3=22](https://img.qammunity.org/2023/formulas/mathematics/college/clr45uz8xjxr3ed8xwbae9wl26wyj9vwg0.png)
Already we knew that the diagonal will be equal with the length 22 units.