17: (3/9+1/4) + (7/8-1/4) * (4/5)

17: (3/9+1/4) + (7/8-1/4) * (4/5) = 29 9/14

1) 3/9+1/4 = (3*4+1*9) / (4*9) = (12+9) / 36=21/36=7/12

2) 7/8-1/4 = (7*1-1*2) / 8=) (7-2) / 8=5/8

3) 17: (7/12) = 17*12/7=204/7

4) 5/8*4/5=4/8=1/2

5) 204/7+1/2 = (204*2+1*7) / (7*2) = (408+7) / 14=415/14=29 9/14