Answer:
(10 * 312) + (10 * 612) + (10 * 812)
Explanation:
To find the total amount of shampoo that Christa purchased in ounces, we can use the expression (10 * 312) + (10 * 612) + (10 * 812), which is equivalent to the expression that Christa used. This expression is also equivalent to 3120 + 6120 + 8120, which can be simplified to 3120 + 6120 + 8120 = 3120 + 6150 + 8100 = 9280 + 6150 = 15,430. Therefore, the expression (10 * 312) + (10 * 612) + (10 * 812) is equivalent to 15,430.