Hey there!
The answer to your question is 
Given:

First, we can start by adding like terms. The following are like terms:



Now, we can add these pairs together, giving us:



Now, add all this together, and we get our answer as:

Have a terrificly amazing day!
79.8? I'm not sure, but just a guess :)
The measure of length SV is 60 units
<h3>Isosceles Right Triangle</h3>
An Isosceles right triangle is a right triangle that has equal opposite and adjacent sides.
The above means that:

Substitute values for SV and ST

Subtract z from both sides

From the figure, we have:

Substitute 30 for z


Hence, the measure of length SV is 60 units
Read more about isosceles right triangle at:
brainly.com/question/3956010
Step-by-step explanation:
1. Choose arbitrary points A and B in the plane and draw segment AB.
2. Raise a perpendicular m to AB at A.
3. Raise a perpendicular n to AB at B.
4. Choose an arbitrary point C on line n.
5. Drop a perpendicular from point C to line m. Let D be the foot of this perpendicular.
6. Then quadrilateral ABCD is a rectangle.