Let's have the first number be x, the second number y, and the third number z.
Because the second number is six more than the first, y = x + 6.
Because the third number is twice the first, z = 2x.
The three numbers added together equals 26, so 26 = x + y + z.
Let's substitute y = x + 6 and z = 2x into 26 = x + y + z. This gives us:
26 = x + x + 6 + 2x
26 = 4x + 6
We subtract 6 from both sides of the equation and divide by 4 to get:
5 = x
Now, we'll put x = 5 into our previous to equations to find y and z:
y = 5 + 6
y = 11
z = 2*5
z = 10
Let's check out answer. 10 + 11 + 5 = 26. 10 is twice of 5 and 11 is 6 more than 5. Thus our three numbers are 10, 11, and 5.