Question

Suppose y varies directly with x, and y= 10 when x=-2. What direct variation equation relates x and y? What is the value of y when x=-15. I don't understand how to solve this, can someone explain to me how to get the answer and what it's asking. P. S. It's a practice question so i know the answer just not how to get it

Answer 1

y = 75

Explanation:

`y=kx\\10=k(-2)\\10=-2k\\k=-5\\\\y=-5x\\y=-5(-15)\\y=75`

When y varies directly with x, this means that you need to set up the equation y=kx and solve for k given (x,y)=(-2,10) and then use your new equation to plug in x=-15 to get y=75