The number is 84.
Assign the digits in the number the letters a and b.
GIVEN: a + b = 12
GIVEN: a = 2b
Solve for b, then solve for a.
2b + b = 12
3b = 12
b = 4
a = 2(4) = 8
9218 9425
The number is 84.
100012
There is a lot of answer for this, but I tell you one. The answer is 6541.
12
22621, 44742, 66863, 88984
804
2,241 because you double the digits
9218 9425
22621, 44742, 66863, 88984
81
91 since the ones digit is 8 less than 9 and the two digits, 9+1 = 10, a two-digit number.
216.
2
216
The number is 84.
1