Start by drawing your basic pant with 2cm wearing ease at waist circumference and 4cm ease at hips.

On back, widen 1 to 1,5cm from crotch point and drop it by 1 to 2cm. Square down from this new point to hemline, then on side seam square down from hip level to hemline.

On front, widen at crotch by 0,3 to 0,5cm and drop it by the same measurement used on back, then square down from crotch. On front waist add 1 to 1,5cm (this amount will be balanced by a new dart) and add the same amount to hip level at side seam. Square down from this new point to hemline.

Get back and cut through the new lines or trace a copy of the whole piece.

Draw a line 2,5cm below waistline, and draw a line 2,5cm above waistline. This 5cm section is going to be the waistband. Dart extends into the waistband and the lines above waist are perpendicular to the waistband upper line (i.e. dart width is consistent in the area above waist).

Trace a copy of the waistband and cut through dart lines.

Tape dart closed on the waistband and trace a copy of it.

Center back waistband will be cut on fabric fold, so make sure its angles are right.

Back pant is ready, eventually you could add pockets (I would suggest a single welt one).