Answer:
I think 7
Step-by-step explanation:
4 , 8 , 9 and 12 has factors.
7 has no factor.
4= 2×2
8= 2×4
9= 3×3
12= 3×4
Answer: 
<u>Step-by-step explanation:</u>
Note the following identities: tan² x = sec²x - 1

tan² x + sec x = 1
(sec² x -1) + sec x = 1
sec² x + sec x - 2 = 0
(sec x + 2)(sec x - 1) = 0
sec x + 2 = 0 sec x - 1 = 0
sec x = -2 sec x = 1

I think it is 13 by looking at the angle and numbers.
Answer:
9
Step-by-step explanation:
The factors of 18 are : 1, 2, 3, 6, 9, 18
The factors of 27 are : 1, 3, 9, 27
The common factors are : 1, 3, 9
The gcf is 9
Answer:
45 old houses
Step-by-step explanation:
new houses : old houses
3 : 9
15 : ?
(3 = 1st ratio and 9 = 2nd ratio)
To find the missing ratio, divide the first ratio from the new ratio:
15 / 3 = 5
Take the product and multiply that by the second ratio to find the missing ratio:
9 x 5 = 45