Question

Write an appropriate direct variation equation if y = 30 when x = -10.

A. Y= -300x
B. Y= 3x
C. Y = -3x
D. Y = 300x

Answer 1

direct variation means you can write the equation
y = k x
where k is some number.

to find k, we need to know an x,y pair that is true for this equation
luckily they tell us when x=-10 then y is 30
replace x with -10 and y with 30 and get
30 = k * -10

to find k, divide both sides by -10
can you do that ?