$\\$
`a,`
`( (-3)/5 + 5/11) : (-3)/7 + ( (-2)/5 + 6/11) : (-3)/7`
`= ( (-3)/5 + 5/11) . (-7)/3 + ( (-2)/5 +6/11) . (-7)/3`
`= [(-3)/5 + 5/11 + (-2)/5 + 6/11] . (-7)/3`
`= [( (-2)/5 + (-2)/5)+ (5/11+6/11)] . (-7)/3`
`= [-1 +1] . (-7)/3`
`= 0 . (-7)/3`
`= 0`
$\\$
`b,`
`( (-2)/5 +1/4 : (-7)/101) . (55/17 - 4/7 . 2/3) . (1 - 5/13 : 5/13)`
`= ( (-2)/5 +1/4 : (-7)/101) . (55/17 - 4/7 . 2/3) . (1-1)`
`= ( (-2)/5 +1/4 : (-7)/101) . (55/17 - 4/7 . 2/3) . 0`
`= 0`
$\\$
`c,`
`(-5)/9 . 3/11 + (-13)/18 . 3/11`
`= ( (-5)/9 + (-13)/18) . 3/11`
`= ( (-10)/18 + (-13)/18) . 3/11`
`= (-23)/18 . 3/11`
`=(-23)/66`
$\\$
`d,`
`(3/4 - 3/5+3/7 + 3/11)/(13/4 - 13/5 +13/7 + 13/11)`
`= ( 3 . 1/4 - 3 . 1/5 + 3 . 1/7 + 3 . 1/11)/(13 . 1/4 - 13 . 1/5 +13 . 1/7 + 13 . 1/11)`
`= (3 . (1/4 - 1/5 + 1/7+1/11) )/(13 . (1/4 - 1/5 +1/7 + 1/11) )`
`= (3 . 1)/(13 . 1)`
`=3/13`