X+6=18 its hard to solve

Look at this expression. a3b3c a-3b-3c-1 which of the following is the simplest form of the expression above?

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).

Type the correct answer in each box. spell all the words correctly, and use numerals instead of words for numbers. if necessary, use / for the fraction bar(s).