3x + 2y = a
5x + y = b
eliminating the variable y from the system of equations results in -7x =
a - 2b
2b - a
a + 2b

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

We just started the introduction into circles and i have no idea how to do this.

Find the distance between (7,-6) and (-3,-9)