Answer:
a≤39/5
Step-by-step explanation:
60a - 80a ≥ -64 -92
-20a≥-156
a≤156/20
a≤39/5
Step-by-step explanation:
-2 x 3/7 = (-2 x 3) /7
= -6/7
Answer:
D. Infinitely many solutions
Step-by-step explanation:

1.Since neither equation contains an isolated. However, we can isolate -y in the first equation by adding
to both sides.
Like this: 
ending up with 
2.Now, we can change y to a positive y. By doing so, we divide -y by the entire equation.
Like this 
Ending with 
3.Now, we can plug the expression
into the second equation as a substitute for y, and solve for x. Then, we can use x to calculate y.
Like this 
4. Since -2x+2x would cancel out and leave -30=-30. This is true because we know -30 equals -30 with no variable in sight.
150 degrees because supplementary angles add up to 180 degrees
Hello,
f(x,y)=4cos x sin y-2
@f/@x=-4sin x sin y
@f/@y=4 cos x cos y
dy/dx=-(@f/@x)/(@f/@y)=sin x sin y/(cos x cos y)=tg x * tg y