Just borrow from the 7 and take the 1 to the 2 and that will make it as 12 so then you subtract 12 - 4 and the answer will be 1,180
Take 3/7 and multiply it by 2 to find out how much she knits in one hour. Then take that value and multiply by 12 to find out how much she knits in 12 hours.
3/7 x 2 = 6/7
6/7 x 12 = 72/7 or 10 2/7.
D = P - 2.50
D is price after coupon is used, P is price before