C = -20
dC = 5

while C <= 40:
    F = (9.0/5)*C + 32
    #print with 6 digits in total, 2 decimals:
    print('%6.2f %6.2f' %(C,F))
    C = C + dC

"""
Terminal> python c2f_table_while.py
-20.00  -4.00
-15.00   5.00
-10.00  14.00
 -5.00  23.00
  0.00  32.00
  5.00  41.00
 10.00  50.00
 15.00  59.00
 20.00  68.00
 25.00  77.00
 30.00  86.00
 35.00  95.00
 40.00 104.00
 """