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Adj has a total of 1075 dance and rock songs on her system. the dance selection is 4 times the size of the rock selection. write a system of equations to represent the situation.

The half-life of iodine-131 is approximately 8 days. find the amount of iodine-131 left from a 42 gram sample after 16 days. a: 10.5 grams b: 21 grams c: 0.0006 grams d: 34 grams

On tuesday, a local hamburger shop sold a combined total of 375 hamburgers and cheeseburgers. the number of cheeseburgers sold was two times the number of hamburgers sold. how many hamburgers were sold on tuesday?