1. As you can see in the figure attached, the line "t" is the perpendicular bisector of JK, and divides the triangle in two equal right triangles. This means that both triangles are congruent. Therefore, both have equal dimensions. Keeping this on mind, you have the followiig:
2. Both triangles are congruents, then:
GK=GJ
3. So if the lenght GK is 8.25, the length GJ has the same length:
GJ=8.25
4. Therefore, the answer is:
GJ=8.25