Rút gọn các biểu thức sau (với a > 0, b > 0):

$5\sqrt{a}-4b\sqrt{25a^3}+5a\sqrt{16a{b}^2}-2\sqrt{9a}$

Choose the best answer.

I think you should buy _____  pack of mineral water instead. And you can also buy _____  snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ______  cookies and soft candies.

Choose the best answer.

We should decorate our living room with _____ orange banner. We also need ________  ribbons, balloons, party hats and costume.

Choose the best answer.

I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.