If y varies directly as x, and y=42 as x=6, how do you find y for the x-value 3?
Direct variation can be represented as:
so substituting :
Now, we have the value of
By cross multiplying we get
on observing the values
# x = 6 , color(red)(y) = color(green)(7)xx6= 42#
# x = 3 , color(red)(y) = color(green)(7)xx3 = 21#