Presented here are summarized data from the balance sheets and income statements of Wiper Incorporated:

$\backslash$table$[[\backslash$table$[[$WIPER INCORPORATED$],[$Condensed Balance Sheets December $31,2023,2022,2021($in millions$)]]],[,2023,2022,2021],[$Current assets,$ $821,$$ $1,061,$$ $923],[$Other assets,$2,432,1,939,1,738],[$Total assets,$ $3,253,$$ $3,000,$$ $2,661],[$Current liabilities,$ $596,$$ $849,$$ $751],[$Long$-$term liabilities,$1,631,1,106,973],[$Stockholders$\text{'}$ equity,$1,026,1,045,937],[$Total liabilities and stockholders' equity,$ $3,253,$$ $3,000,$$ $2,661]]$

$\backslash$table$[[\backslash$table$[[$WIPER INCORPORATED$],[$Selected Income Statement and Other Data For the Years Ended December $31,2023$ and $2022($in millions$)]],2022],[$Income statement data:$],[$Sales$,,3,069,$$ $2,932],[$Operating income,,$315,329],[$Interest expense,,$103,84],[$Net income,,$248,243],[$Other data:$],[$Average number of common shares outstanding,,$43\mathrm{.}2,48\mathrm{.}6],[$Total dividends paid,,$ $69\mathrm{.}0,$$ $54\mathrm{.}2]]$

Required:

a$.$ Calculate return on investment, based on net income and average total assets, for $2023$ and $2022.$

b$.$ Calculate return on equity for $2023$ and $2022.$