Let us first establish what has happened here. Emma brings two bottles of shampoo which are initially believed to have the same amount of shampoo. She used the champu's 3/8 volume of the first bottle and the remaining champu's 7/10 which I assume is the second bottle of champu after Emma first bring two bottles of champu. As the question asks for the remaining amount of shampoo, it seems that at the start of this problem the denominator which is the total shampoo amount in both the bottles must add both the fractions 3/8 and 7/10 to find the remaining amount of shampoo.
So it can be set up 3/8+7/10 as the eighths are more than tenth as fractions.
The same denominator has to be found by filling in 7/10 8 and 3/8 10 for number and denominator for both fractions. Then we get it
30/80+56/80=86/80। Suppose she used only the first bottle then 86/80 is the answer which show that she used the entire bottle.