Can someone teach me about percent increases and decreases with equations?

The square root of 9x plus 7 plus the square rot of 2x equall to 7

Which two fractions are equivalent to 24/84? 6/42 and 2/7 6/21 and 2/6 12/42 and 3/7 12/42 and 2/7

The dance committee of pine bluff middle school earns $72 from a bake sale and will earn $4 for each ticket they sell to the spring fling dance. the dance will cost $400 write an inequality to determine the number, t of tickets the committee could sell to have money left over after they pay for this year's dance. what is the solution set of the inequality?