面倒めんどうな計算けいさんは弟おとうとに任まかせたよ。

mendou na keisan wa otouto ni makaseta yo.

I left the fiddly calculations to my little brother. casual

細こまかい調整ちょうせいは担当たんとうの者ものに任まかせております。

komakai chousei wa tantou no mono ni makasete orimasu.

We leave the finer adjustments to the member of staff in charge. formal