Tina would like to melt down her existing gold to make a 20ounce gold necklace t

Tina would like to melt down her existing gold to make a 20ounce gold necklace that is 90% pure gold. After melting herjewelry she is left with two batches. One batch is 75% pure. Theother batch is 96% pure. How much of the 96% pure gold should Tinamix with the 75% pure gold to obtain the 20 ounces of 90% puregold?