The fire department has seen an increase in smoke detector sales since 2015. In 2015, they sold 350 detectors which is up from the previous year by 105%. How many did they sell in the previous year?

Answer: the correct answer is 10step-by-step explanation: let the number be n, then the expression becomes,then“twelve more than the quotient of a number and two, decreased by four” iswhen n=4,we substitute 4 whetever we see n to get,we simplify to obtain,we further simplify to get,therefore the correct answer is c.

31/6= 19/6 19/6 *1/7=19/42