ST is a midsegment, which tells you that BD=2(ST) or ST=½BD. Use that to substitute the values and find ST. BD=2(ST) 29+x=2(2x+31) 29+x=4x+62 29=3x+62 -33=3x x=-11 Now that we know x, we can substitute that into 2x+31 to find ST ST=2x+31 ST=2(-11)+31 ST=-22+31 ST=9
