What is the best common denominator for 3/4 + 5/6

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

Someone this asap for a group of students attends a basketball game. * the group buys x hot dogs at the concession stand for $2 each. * the group buys y drinks at the concession stand for $3 each. the group buys 29 items at the concession stand for a total of $70. how many hot dogs did the group buy?

What function has a range {yly< 5}? question on picture above^