Write the results of each of the following in scientific notation. a$.(5*{10}^{15})(8*{10}^{17})$ b$.(9*{10}^{12})(3*{10}^8)$ c$.(5*{10}^8)(4*{10}^9)(10*{10}^{10})$ a$.(5*{10}^{15})(8*{10}^{17})=($Use scientific notation.$)$