25 is the answer to your question
x = player1
y = player 2
z = player 3
y = 2x or 1/2 y =x
y = z-10 or z = y+10
x+y+z=70
substitute x= 1/2 y and z = y+10 into the above equation
1/2y + y + y+10 = 70
2.5 y + 10 = 70
subtract 10 from each side
2.5 y = 60
divide by 2.5 on each side
y = 60/2.5
y =24
x = 1/2 y
x = 1/2 *24 = 12
z = y+10 = 24+10 = 34
The three players scored 12, 24, 34
In the general case, it is (x, y+3), where y = f(x).