Marc has 45 cds in his collection, and corinna has 61. if marc buys 4 new cds each month and corinna buys 2 new cds each month, after how many months will marc and corinna have the same number of cds write an equation to solve

Quadrilateral abcd in the figure below represents a scaled-down model of a walkway around a historic site. quadrilateral efgh represents the actual walkway. abcd is similar to efgh. what is the total length, in feet of the actual walkway?

Is it greater than or less than7*3_9*2

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?