Answer:
x =70
Step-by-step explanation:
The variation model we'll need here is y = kxz, where k is the constant of proportionality. We are told that when y = 105, x = 2 and z = 9. This gives us enough info with which to calculate k:
9 = k(2)(9), or 1 = 2k, or k = 1/2.
Then the governing equation is
y = (1/2)xz.
If y = 105 when z = 3, then we have 105 = (1/2)(x)(3).
To solve this for x, first multiply both sides by 2, obtaining 210 = 3x.
Finally, we divide both sides by 3, obtaining the final result x = 70
