Please help me ITS DUE PLEASE

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%.

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

1.two more than the quotient of a number and 6 is equal to 7 use the c for the unknown number translate the sentence into an equation