In need to know how to solve these can't really understand how

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.]

answer: 4  

the square root of 16 is 4. it is a very simple mathematic concept. a square root when a number multiplied by itself will result in a number. here, the number 16 comes when 4 is multiplied by 4. hence the square root of 16 is 4. you can always figure out a square root by the inverse operation of squaring.