`11/24 - 25/31 + 13/24 + 0,5 - 37/21`
`=11/24 - 25/31 + 13/24 + 1/2 - 37/21`
`=(11/24 + 13/24) + (-25/31 - 37/21) + 1/2`
`=` \(\left(\dfrac{11+13}{24}\right)+\left(\dfrac{-525-1147}{651}\right)+\dfrac{1}{2}\)
`=24/24 + (-1672)/651 + 1/2`
`=1 -1672/651 + 1/2`
`=-1021/651+1/2`
`=-1391/1302`