The sum of two numbers is 17 and their difference is 3.
Let's define the two numbers as x and y.
Sum of two numbers is 17
x + y = 17
Their difference is 3
x - y = 3
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Solve for x
x + y = 17
x = 17 - y
now that we have x, substitued x into x - y = 3
x - y = 3
17 - y - y = 3
17 - 2y = 3
-2y = -14
y = 7
we have y, 7, now let's substitue that into one of the equations to find x
x - y = 3
x - 7 = 3
x -7 + 7 = 3 +7
x = 10
the numbers are 10 and 7