Answer:

Explanation:
To find the coordinates of endpoint B, we can use the midpoint formula. The midpoint formula is given by:

In this case, the coordinates of A are
and the coordinates of R (the midpoint) are
. The coordinates of B are
.
Let's use the midpoint formula to solve for
:

Now, we can solve for
and
:
1. Solve for
:

Multiply both sides by 2:

Add 5 to both sides:

2. Solve for
:

Multiply both sides by 2:

Subtract 16 from both sides:

So, the coordinates of the endpoint B are
.