Consider this option: 1. area_rombus=a*h, where a=6 - the length of the side, h - height. h=area_rombus/a. 2. area_sq=a², where a=6 - the length of the square. area_sq=36, area_rombus=4/5 *36=28.8. 3. according to the item 1 h=area_rombus/a=28.8/6=4.8.
