Question 32842
First, we set up our general equation. Because y is directly proportional to x, we have: y = cx

where c is the constant of proportionality. In other words, when x goes up, y goes up, and when x goes down, y goes down. 

so here lets assume when x = 2000 , y = 120,000
so we need to find the value of x when y = 180,000

y = cx
120,000 = c (2000)
c = 120,000/2000 = 60

therefore when c = 60 and y = 180,000
180,000 = 60 (x)
x = 180,000/60 = 3,000

When the revenue is 180,000 the amount spent on advertising is $3000