how do you calculate :

Calculate the new selling price that equal to previous year contribution margin ratio:

The new selling price can be calculated by dividing modified variable cost by one minus difference between previous selling price and variable cost by previous selling price. It is given that the modified variable cost is $23.80 and previous variable cost is $21. The previous selling price is $35. It is required to calculate the new selling price

New selling price =

How do I calculate this?