2y+ 3x = 87 and y=6x+21

Marco is studying a type of mold that grows at a fast rate. he created the function f(x) = 345(1.30)x to model the number of mold spores per week. what does the 1.30 represent? how many mold spores are there after 4 weeks? round your answer to the nearest whole number. 1.30 represents the number of mold spores marco had at the beginning of the study; 985 mold spores 1.30 represents the number of mold spores grown in a given week; 448 mold spores 1.30 represents the 30% rate of weekly growth; 345 mold spores 1.30 represents the 30% rate of weekly growth; 985 mold spores

Me complete this proof! prove that a quadrilateral is a square. me with the steps for this proof.

8. kelly wants to buy a magazine that is $25. later the magazine was marked up an additional 20%. what is the new price?