Question 9, you have the right method but 3+6+7+5 = 21 not 20 so your probability would be 3/21 = 14.3%
Question 10, once again you're doing the right thing by listing out what numbers each dice can have. I will draw what you have drawn in a slightly different way which hopefully might make it easier. (See image attached.)
This is called a two-way table. Which numbers occur most often on the two way table?