Answer:
![UV=8\ units](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ezqxa07daxkoqytvp1ed8cg7dgqktzgbkz.png)
![XY=16\ units](https://img.qammunity.org/2021/formulas/mathematics/middle-school/bkz51ug1dtskgl1nk8hv5zepb9zvsf73vv.png)
![TW=24\ units](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ccsbler0g0hu6ayaq8etvckzt116131jfy.png)
Explanation:
we know that
In this problem
XY is the mid-segment of trapezoid TUVW (because K is the midpoint segment TU and Y is the midpoint segment VW)
Remember that the length of the mid-segment is the sum of the two parallel bases divided by 2
so
![XY=(UV+TW)/(2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/x2hpuf7yt0nj45mhm31h0p59nwvxnazs5z.png)
substitute the given values
![3x+7=(3x-1+8x)/(2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/b2l8lx4o56w4jp8sks4rxqwelm8qlj3tx3.png)
solve for x
Multiply by 2 both sides
![6x+14=11x-1](https://img.qammunity.org/2021/formulas/mathematics/middle-school/xvnpi65wnkqrrssinwkxik20chlqoyj3m8.png)
![11x-6x=14+1](https://img.qammunity.org/2021/formulas/mathematics/middle-school/j8zx9l2v4bzijgfemoyg1y033n1hzycgsn.png)
![5x=15](https://img.qammunity.org/2021/formulas/mathematics/middle-school/yf4950etr722rxz5cefxhzvh07k5n93lob.png)
![x=3](https://img.qammunity.org/2021/formulas/mathematics/college/yzekanmiuar9edsve93wg5dpqbw3650n5b.png)
Find the length segment UV
![UV=3x-1](https://img.qammunity.org/2021/formulas/mathematics/middle-school/r7jx3j9j2890dl55rkqpuoxyog2v1wh0f1.png)
substitute the value of x
![UV=3(3)-1=8\ units](https://img.qammunity.org/2021/formulas/mathematics/middle-school/nm25467k7vfg87u1bjalyeziky7wqk1j9l.png)
Find the length segment XY
![XY=3x+7](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ef5r9bh26md99ab8ruhn1bq22x3oksvgq5.png)
substitute the value of x
![XY=3(3)+7=16\ units](https://img.qammunity.org/2021/formulas/mathematics/middle-school/6n1dbiscjwdof16rg3svmc1n5zjsuoqnop.png)
Find the length segment TW
![TW=8x](https://img.qammunity.org/2021/formulas/mathematics/middle-school/a65fc7ov5f44hb0i8jjd2xnzpg0j94jclj.png)
substitute the value of x
![TW=8(3)=24\ units](https://img.qammunity.org/2021/formulas/mathematics/middle-school/m8ctsysnify9ti355zttd0aoy6908mfusl.png)