Dividing bill cost in relation to incomes formula

Hi i wasn't sure where to post this does any body know of a online calculator or a formula to calculate how household bills should be paid in relation to two peoples incomes



Say person 1 has a weekly wage of £90 and person 2 has a weekly wage of £300



In pre potion to there incomes how would a weekly rent bill of £80 be split?



Does anybody know the formula for this? please help

Dividing bill cost in relation to incomes formula