Write a direct variation equation when x relates to y and y= 10 and x=2. Then find the value of y when x= 8

Question

direct variation is when you have the formula y=kx and when it constant

Answer 1

1. this is a proportions problem

2. since y and x vary directly, y = k*x

3. thus, 10 = k*2, and 5 = k

4. now, let's use our new value for x to solve for y

5. y = k*x, so y = 5*x

6. let's plug in x = 8

7. y = 5*8 = 40

8. note, the proportions are equal: y/x = k, 10/2 = 5, and 40/8 = 5

9. y = 40 when x =8