-3(x+5)=-9
-3x-15=-9
+15 +15
-3x=6
-1x=2
1x=-2
x=-2
15. -2
16. A. The pool was originally empty
Step-by-step explanation:
tanB + cotB = (sinB)/(cosB) + (cosB)/(sinB)
= (sin2B + cos2B)/[(cosB)(sinB)]
= 1/[(cosB)(sinB)]
= (1/cosB)(1/sinB)
= (secB)(cscB)