I need assistance solving this for Algebra 2: 9 + ex = 12 solve

In two or more complete sentences describe how to determine the appropriate model for the set of data, (1,1), (3,2), (6,3), (11,4).

Florence price's brownies and more sells all types of cookies and pastries. on tuesdays, they markdown all brownies 75% to a sale of $1.50 a dozen. find the selling price and the markdown of a dozen brownies.

The sum of these consecutive integers is equal to 9 less than 4 times the least of the integer. find the three integers