Answer:

Step-by-step explanation:
Factor out 7 from top and bottom :

Divide top and bottom by 7 :

Simplify :
Simplify :
Collect everything together :

Hope this helped and have a good day
The answer:
First: sec(-pi) is sec(pi)
And sec(pi) is -1
Y=(kx)/z
15=(k10)/4
15=(5k/2)
15=k(5/2)
ties both sides by 2/5 to clear fraction
6=k
y=(6x)/z
x=20
z=6
y=(6*20)/6
y=20
Answer:
18
Step-by-step explanation:
÷ 
Keep Change Flip
×
= 
Answer:21
Step-by-step explanation:12 times three is 36 and 7 times 3 is 21