(15 - 2 3/7)-(8 2/7+ 1 4/7)
1) 15- 2 3/7= 12 4/7 2) 8 2/7+ 1 4/7= 9 6/7 3) 12 4/7- 1 4/7 = 2 5/7
(15- 2 3/7)-(8 2/7+ 1 4/7)=(105/7-17/7)-(58/7+11/7)=88/7-69/7=19/7=2 5/7