Forcum Company reports the following information $($in millions$)$ during a recent year: net sales, $$12,408\mathrm{.}5$; net earnings, $$344\mathrm{.}9$: total assets, ending,$$4\mathrm{.}312\mathrm{.}6$; and total assets, beginning,$$4\mathrm{.}254\mathrm{.}3.$

$($a$)$Calculate the $(1)$ return on assets $(2)$ asset turnover and $(3)$ profit margin ratios

$($b$)$ Prove mathematically how the profit margin and asset turnover ratios work together to explainreturn on assets, by showing the appropriate calculations