in examples like question 4, just combine the fractions on the side with more than one fractions into one whole single fraction first.
(2k + 5) / 5 = (3k + 1) / 2 + (-k +7) / 2
(2k + 5) / 5 = (3k + 1 - k + 7) / 2
(2k + 5) / 5 = (2k + 8) / 2
then, cross-multiply both sides.
10k + 40 = 4k + 10
6k = 30
k = 5
[basically put like terms together and make them into a single fraction. if separated by an equal sign, cross multiply and simplify the equation.]
