In a proportional relationship, x and y will increase at the same rate. In order to find the value of x when y=4, we first have to find the ratio of x:y. We can do this by creating a fraction. After we know the ratio, simply replace the y value with 4 and solve for x. Here's the math:
y=15 when x=3 given values
y/x = 15/3 = 5 ratio of y to x
y=5x equation representing the proportional relationship
4=5x replace y with 4
4/5=x divide both sides by 5 to isolate x
Answer: The value of x=4/5 when y=4.
Hope this helps!
