13. For this pattern, we start with 4, and then the next number in the sequence is 20. How do 4 and 20 relate to each other?
Well, 4 * 5 = 20, so let's see if that's what the pattern is...
20 * 5 = 100
What's the next number in the sequence? 100, so it looks like that is what the sequence is.
100 * 5 = 500
Yep :D
The pattern for 13 is multiply by 5.
14. For this one, we start with 44, then go to 22. We know that 44 divided by 2 is 22. But 22 divided by 2 is 11, not 20, so what would the next step be? Well, 22 minus 2 is 20, so let's see what we have to work with after this. 20 divided by 2 is 10, which is the next number in the sequence, and 10 minus 2 is 8.
The pattern for problem 14 is divide by 2, then subtract 2, and repeat.
19. The expression is 7 + 3 * 6 = ?
According to the Order of Operations (PEMDAS), we need to do any multiplication in the problem before addition.
3 * 6 = 18
7 + 18 = 25
7 + 3 * 6 = 25
20. The expression is (6 - 4) * 9
Again, referring to PEMDAS, we can see that items in parentheses come first.
6 - 4 = 2
So now the problem is 2 * 9 = ?
2 * 9 = 18
So,
(6 - 4) * 9 = 18
Hope that helped =)