we have the segment ST
see the attached figure to better understand
ST=SP+PT -----> by addition segments postulate
P is the midpoint
that means
SP=PT
therefore
ST=2SP
substitute given values
4x=2(x+4)
4x=2x+8
4x-2x=8
2x=8
x=4
the length of segment ST is 4(4)=16 units
therefore
the answer is
If P is the midpoint of ST. SP = x + 4, and ST = 4x, determine the length of ST.
ST=16 units
SP=8 units
