Find the value of the following sum:

What is the value of 'k' in the following sum? 57 + 54 + 51 +..........+ k = -123

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

Find the sum of ∠a, ∠b, ∠c and ∠d in the following image?