context: ###List of Questions
  (1) Let x be 49/21 + (-2)/(-3). Suppose 31 = d - 2*u, -x*d + u = -u - 89. What is the units digit of d?
  (2) Calculate prob of sequence fffm when four letters picked without replacement from fffffmmmmmmmm.
  (3) How many millilitres are there in eleven eighths of a litre?
  (4) Solve 4*f + 4*z = 0, 0 = -28*f + 29*f - 2*z + 15 for f.
  (5) What is -0.4 plus -49.921?
q_1: (1) Let x be 49/21 + (-2)/(-3). Suppose 31 = d - 2*u, -x*d + u = -u - 89. What is the units digit of d?
q_2: (2) Calculate prob of sequence fffm when four letters picked without replacement from fffffmmmmmmmm.
q_3: (3) How many millilitres are there in eleven eighths of a litre?
q_4: (4) Solve 4*f + 4*z = 0, 0 = -28*f + 29*f - 2*z + 15 for f.
q_5: (5) What is -0.4 plus -49.921?