from sys import stdin
input=lambda :stdin.readline()[:-1]

def calc(n,p):
  dp=[0]*(n+1)
  for i in range(1,n+1):
    s=p*i//m
    dp[i]+=s
    if dp[i]==0:
      continue
    for j in range(2*i,n+1,i):
      dp[j]-=dp[i]
  return sum(dp)

m=1<<40
def solve():
  n,k=map(int,input().split())
  c=calc(n,m-1)
  if k==c+1:
    print('1/1')
    return
  if k<=c:
    rev=False
  elif k<=2*c+1:
    rev=True
    k=2*c+2-k
  else:
    print(-1)
    return
  ng,ok=0,1<<40
  for _ in range(38):
    mid=(ok+ng)//2
    if calc(n,mid)>=k:
      ok=mid
    else:
      ng=mid
  
  ans=-1
  for p in range(1,n+1):
    q=(ok*p)//m
    if m*q>ng*p:
      if rev:
        p,q=q,p
      print(str(q)+'/'+str(p))
      return
    
  raise Exception

for _ in range(int(input())):
  solve()