Anybody know this pls I need help

Solve for n? [tex]z = \frac{3}{4} mn[/tex]

Find the domain of the following expression: 1/(√x)-2

Acampus club held a bake sale as a fund raiser, selling coffee, muffins, and bacon and eggs sandwiches. the club members charged $1 for a cup of coffee, 3$ for a muffin , and $4 for a back. and egg sandwich. they sold a total of 55 items , easing $119. of the club members sold 5 more muffins than cups of coffee, how many bacon and egg sandwiches he’s did they sell