The simultaneous equations (1) and (2) have at least two distinct (x,y) solutions. 2x+5y=a−b (1) 4x+10y=a+b (2) The simultaneous equations (3) and (4) also have at least two distinct (x,y) solutions. 3x−2y=a−b+4 (3) 9x−6y=a+4b−1 (4) What is the value of 10a+b?
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