`a)`
`13 1/4 :(-5/7)-18 1/4 :(-5/7)`
`= (13 1/4 - 18 1/4):(-5/7)`
`= -5 :(-5/7)`
`=-5.(-7/5)`
`= 7`
`b)`
`(7 + 3/2-1/3)-(1/2+2/3-2)-(5+1/3)`
`= 7 + 3/2 - 1/3 - 1/2 - 2/3 + 2 - 5 - 1/3`
`= (7+2-5)+(3/2-1/2)+ (-1/3-2/3-1/3)`
`= 4 + 1 - 4/3 `
`= 5 - 4/3`
`= 11/3`
`c)`
` 3/5 + 13/25-5/9-6/14`
`=3/5+13/25-5/9-3/7`
`= 15/25+13/25-5/9-3/7`
`= 28/25-5/9-3/7`
`= 1764/1575-875/1575-675/1575`
`=214/1575`
`d)`
`(-7/15+5/7):4/3+(2/7-8/15):4/3`
`=(-7/15+5/7+2/7-8/15):4/3`
`= [(-7/15 - 8/15) + (5/7 + 2/7)]:4/3`
`=(-1 + 1):4/3`
`= 0 : 4/3`
`= 0`