Answer:
Value of x = 5 .
Step-by-step explanation:
Combined variation states that describes a situation where a variable depends on two (or more) other variables, and varies directly with some of them and varies inversely with others.
Given: x varies directly with y and inversely with z.
i.e [tex]x \propto y[/tex] and [tex]x \propto \frac{1}{z}[/tex]
then we have the combined variation as;
[tex]x = k\frac{y}{z}[/tex] ......[1] where k is the constant variation.
Substitute the value of x =20 when y =8 and z = 4 to solve for k;
[tex]20 = k\frac{8}{4}[/tex]
Simplify:
[tex]20 = 2k[/tex]
Divide both sides by 2 we get;
[tex]k = 10[/tex]
Now, substitute k =10 , y =4 and z = 8 to find x;
Using [1] we have;
[tex]x = 10 \times \frac{4}{8} = 10 \times \frac{1}{2} = 5[/tex]
Therefore, the value of x is, 5
