What comes between 1/2 and 2/3

Which equation represents the partial sum of the geometric series?

Adepartment store purchases screen-printed t-shirts at a cost of $5 per shirt. they mark up the price 150% (making the selling price 250% of the store's purchase price) and put them on the sales floor. every month that a t-shirt doesn't sell, the store reduces the selling price by 25%.

The square root of 9x plus 7 plus the square rot of 2x equall to 7