based on Walmart prices in the IN area 1 Fels Naptha Soap Bar grated -LRB-.98) 1 cup washing soda (Great Value BK soda).50 1/2 cup borax $ 2.98 (lifeasmom.com)
Use a paste to scrub the sides of the tub to a sparkling white, or mix a solution of one cup borax with one gallon of hot water to eat away at mold in tile grout. (rismedia.com)
Then create a paste using 1/4 cup table salt, 1/4 cup white vinegar and 1/4 cup borax powder. (styleathome.com)