Step 1. Draw the three given points on a coordinate grid. A representation of the points is shown in the following diagram:
Point T(-8,4) is shown in blue, point U(10,8) is shown in green and point S(10,4) is shown in red.
Step 2. Draw the triangle that is formed between the three points:
Step 3. Find the length of the line ST.
Line ST is the line at the base of the triangle, using the previous diagram from step 2 we count the units that this line has and we will find the length:
The length of ST is 18 units.
Answer: 18 units