Arock contains the radioactive isotope k -40 that decays with a half-life of 1.3 billion years and the radioactive isotope rb-87 that decays with a hlif-lifte of 48.6 billion years. the rock is 100 million years old. the rock currently has 1000 times as many rb-87 atoms as there are k-40 atoms. (that is, neb = 1000 x nk.) when the rock first formed it had m times as many rb- 87 atoms as k -40 atoms. (that is, nrb. o - m x nko.) what is the value of m?