`l)` `( -1/4 + 7/33 - 5/3 ) - ( -15/12 + 6/11 - 48/49 )`
`= -1/4 + 7/33 - 5/3 + 15/12 - 6/11 + 48/49`
`= ( -1/4 + 15/12 ) + ( 7/33 - 5/3 - 6/11 ) + 48/49`
`= 1 - 2 + 48/49 = -49/49 + 48/49 = -1/49`
`e)` `1 - 1/2 + 2 - 2/3 + 3 - 1/3 - 2 - 1/2 - 1`
`= ( 1 + 2 + 3 - 2 - 1 ) - ( 1/2 + 2/3 + 1/3 + 1/2 )`
`= 3 - 2`
`= 1`
`l)` `( -1/4 + 7/33 - 5/3 ) - ( -15/12 + 6/11 - 48/49 )