To a 80mL dissolution 0.05M of K2CrO4, you add 20mL of dissolution 0.01M of AgNO3. In mixing these two dissolutions will the AgCrO4 precipitate?
Ks (AgCrO4) = 1.8 . 10^-12

Work out the number of moles of K2CrO4 added.
Work out the number of moles of AgNO3 added.

Work out the concentration of CrO4^2- in 100 mL (100 mL because you added 80 mL to 20 mL)
Do the same for the concentration of Ag^+.

Then, work out:

[CrO4^2-][Ag^+]^2 = ?

Now, you might ask why power 2. That's because:

Ag_2CrO_4 \rightleftharpoons CrO_4\ ^{2-} + 2Ag^+

of the number 2 in front of Ag^+