as you said, the answer is 3^10

three labs order Xenr, there are seven more labs that can order 3^7 different combinations. Therefore there are 3^7 combinationsb.) Xenr appears promising. How many orders are there where at least 3 labs order Xenr?

Find the number of possible combinations where 3 or more labs by Tsela, which is 3^7 (which equals 2187)c.) The pharmaceutical company announces it's running low on Tsela and only has enough for 2 labs. How many orders from the 10 labs can the company fill?

Now subtract that from the total possible combinations: 59049-2187=56862

so there are 56862 possible combinations if no more than 2 labs can buy Tsela.

make note: 3^10=59049