2.8-(-5.1)
-(-5.1)=5.1
2.8+5.1= 7.9
Is this what you were asking?
Answer:
litrally I don't understand what you are telling
Answer:
a) 
b)
when 
Step-by-step explanation:
since y varies inversely with x.
We need to find the constant, k.
Let's use a point (x,y) on the curve.
We are given an (x,y)=(5,10):
Multiply both sides by 5:

.
So the equation is:

What is y when x=2?

