The first number is 8, the second number is 1 and the third number is 4.
To find all of these, we first need to write a system of equations bsaed on the sentences. For this purpose, we'll use x as the first number, y as the seocnd number, and z as the third number.
x + y + z = 13
2x + 4y + 5z = 40
5x - y = 39
To start solving this, we need to combine the first two equations to get the z term to cancel. Multiply the first equation by -5 and add together.
-5x - 5y - 5z = -65
2x + 4y + 5z = 40
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-3x - y = -25
Now we can combine the new equation along with our 3rd equation to cancel out y and solve for x. Multiply the new equation by -1.
3x + y = 25
5x - y = 39
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8x = 64
x = 8
Now that we have the value of x, we can solve for y using the 3rd equation.
5x - y = 39
5(8) - y = 39
40 - y = 39
-y = -1
y = 1
Now we can find z using the values we got and the first equation.
x + y + z = 13
8 + 1 + z = 13
9 + z = 13
z = 4
