Question 1152295
a = alice's share
b = bob's share
m = mary's share


a + b + m = 25000


their agreement was:
a = 2 * m - 1000
b = m + 2000


replace a and b with their equivalents to get:
a + b + m = 25000 becomes:
2 * m - 1000 + m + 2000 + m = 25000
combine like terms to get:
4 * m + 1000 = 25000
subtract 1000 from both sides of the equation to get:
4 * m = 24000
solve for m to get:
m = 24000 / 4 = 6000


a = 2 * m - 1000 becomes a = 2 * 6000 - 1000 which becomes a = 11000
b = m + 2000 becomes b = 6000 + 2000 which becomes b = 8000


you have:
a = 11000
b = 8000
m = 6000
a + b + m = 11000 + 8000 + 6000 = 25000


your solution is that:
alice earned 11000
bob earned 8000
mary earned 6000