Hi!
Question 10:
[tex]7 \sqrt{3} * \sqrt{5} - 2\sqrt{15} = 7\sqrt{15} - 2\sqrt{15} = 5\sqrt{15}[/tex] and that's the correct answer.
Question 11:
[tex]\sqrt{64} = 8[/tex] is the answer, because this is only solution when the value of the square root is whole number.
Hope this helps!
