SOLUTION: Hello, I need help with this: If y varies directly as x and y = 25 when x = 10, find y when x = 4. Thank you

Algebra ->  Inequalities -> SOLUTION: Hello, I need help with this: If y varies directly as x and y = 25 when x = 10, find y when x = 4. Thank you      Log On


   

Question 91816: Hello,

I need help with this:

If y varies directly as x and y = 25 when x = 10, find y when x = 4.

Thank you
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
If y varies directly as x, you can write this as:
y = kx where k is called the constant of proportionality.
To find the value of k, substitute the given values of y (25) and x (10) and solve for k.
25 = 10k Divide both sides by 10.
k = 2.5
Now you have: y = 2.5x so you can find the value of y when x = 4.
y = 2.5(4)
y = 10