We need to convert the weight into Newtons
150,000 kgs X 10m/s2 (gravitational constant)
= 1,500,000 N
L/D ration is 14:1 so the drag will be 1,500,000 / 14 = 107142.85N
Substitute values in formula
T-D/W = SINTHETA x 100 (to express as a percentage)
300000 -107142.85/1500000 = 0.1285714 X 100
= 12.86%