In order to calculate this question, we will use the reaction quotient Q, which has a very similar formula as the equilibrium formula, but this Q can be calculated not just in equilibrium (where Q = K) but in any part of the reaction, so K is the equilibrium, and Q is what is used to see where the reaction will shift towards until it reaches equilibrium, we can have three possible outcomes:
Q = K, the reaction is already in equilibrium
Q > K, the reaction will proceed in the reverse direction
Q < K, the reaction will proceed in the forward direction
Let's set up the formula:
Q = [products]/[reactants], the brackets mean Concentration of each compound. Now adding our compounds
Q = [BrCl]^2/[Br2]*[Cl2], the BrCl is raised to 2 because we have 2 BrCl in the reaction, this is a rule for the equilibrium formula, we use the coefficient in front of the compound and raise its concentration to this number
Now we need the concentration of each compound, to find it we will use the Molarity formula
M = n/V
M = 0.15/2
M = 0.075M, notice that since we have the same number of moles and volume for every compound, we will have the same concentration for every compound, going back to our formula
Q = [0.075]^2/[0.075][0.075]
Q = 1.0
Since K = 7.0 and Q = 1.0
K > Q, the reaction will proceed in the forward direction in order to increase the concentration of 2 BrCl in order to finally reach Q=K