The function f(x) varies inversely with x and f(x)=0.5 when x = 0.15.
What is f(x) when x = 2.5?

0.03

Step-by-step explanation:

Standard equation of inverse variation:

y = k/x

In function notation it is

f(x) = k/x

We are given f(0.15) = 0.5

0.5 = k/0.15

k = 0.5 * 0.15

k = 0.075

The function is

f(x) = 0.075/x

For x = 2.5,

f(2.5) = 0.075/2.5

f(2.5) = 0.03

0.03

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18