please show detailed steps. will thumbs up if correct! $($answer is NOT $"6\mathrm{.}6,7\mathrm{.}59,7\mathrm{.}9$ or $7\mathrm{.}92")$

A plate with thickness t and a centric hole supports an axial load $P=1250N.$

Determine the radius r $($in mm$)$ of the fillets so that the same stress occurs in the

hole and in the fillets.