7ft = 84in 84 ÷ 15 = 5.6 pieces he can cut from each board. Since .6 is not a whole piece measuring 15 inches long, he can only cut 5 pieces from each board.
So, 5 x 2 = 10
He would be able to cut 10 pieces measuring 15 inches long.
It will be double whatever he can cut from one board, not what he can cut from both boards treated as a single 14ft board. He wants 15 inch pieces. Each board in 7 x 12 = 84 inches. How many 15 inches from 84? 84 / 15 = 5.6. So that is 5 because we have to round down. Since he has two boards the total number is 5 x 2 = 10.
