First, we can subtract 3k on both sides. It is ultimately easier to start by subtracting the term with a variable. This would result in 45=5k+25. Then, we can subtract 25 on both sides to get closer to isolating k. This becomes 20=5k. We can then divide by 5 on both sides. This means that k=4.
The Triangle Sum Theorem states that the sum of the angles of a triangle equal 180°. Therefore, 45° + 62° + k = 180 107° + k = 180 k = 73° The value of k is 73°