If an object was dropped from a height of 405 Meters, find the time it took for the object to hit the ground​

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

60 2(x + 2) in the diagram, gef and hef are congruent. what is the value of x?

Answer asap ill give ! ’ a sample of radioactive material decays over time. the number of grams, y , of the material remaining x days after the sample is discovered is given by the equation y = 10(0.5)^x. what does the number 10 represents in the equation? a. the half-life of the radioactive material, in days b. the amount of the sample, in grams, that decays each day c. the time, in days, it will take for the samples to decay completely d. the size of the sample, in grams, at the time the material was discovered