The variables x and y vary directly. Use the values to find the constant of proportionality, k. Then write an equation that relates x and y. Write any fractions in simplest form. y=20; x=12

k=
y=

y=(5/3)x

Step-by-step explanation:

Since y varies directly with x, then the constant of proportionality is equal to k=y/x. Since y/x=20/12=5/3, then k=5/3. This means the equation to relate x and y is y=(5/3)x

b. an equilateral triangle inscribed in a circle

step-by-step explanation:

we are given the figure of two circles having a triangle inside.

now, we know that,

"when a figure is lying inside an another figure, then the outside figure is known as circumscribed figure and the figure lying inside is referred to as the inscribed figure".

as we see that, the circles are containing the triangle completely.

thus, the circles are the circumscribed figures and the triangle is the inscribed figure.

hence, we get, 'an equilateral triangle is inscribed in a circle'.