Y is directly proportional to x

If y= 10 when x=-5 what is the value of y when x =30. The answer should be a number.

3 answers

"Y is directly proportional to x" ---> y = kx, where k is a constant
you are given x=-5, y = 10

so

10 = k(-5)
k = -2
then y = -2x

so when x = 30
y = -2(30) = -60
Thanks. i got -60 the first time, but when i was checking it I was getting -6 so I'll have to see what i was doing wrong! Thanks!!
Y=30 when x=6 what is value of y when x=5