To calculate this expression, we first need to convert the angles to radians.

sin(10') = sin(10pi/180) ≈ 0.1736
sin(80') = sin(80pi/180) ≈ 0.9848
tan(50') = tan(50*pi/180) ≈ 1.1918

Now, let's plug these values into the expression:

sin(10') - sin(80')tan(50')
≈ 0.1736 - 0.9848 1.1918
≈ 0.1736 - 1.1739
≈ -1.0003

Therefore, sin(10') - sin(80')*tan(50') ≈ -1.0003.