Butterick 4107; ca. 1980s; Misses' Tapered Pants or Knickers with design variations all have straight waistband with self belt carriers. Mock fly front zipper closing. Side Seam pockets and top stitching.
Links to reviews/blog posts
Sources/Vendors
mbchills modern and vintage sewing patterns
allthepreciousthings on EtsySize 14 FF