Question

A two digit number has the property that the units digit is 4 less than the tens digit and the tens digit is twice the units digit. What is the number?

Answer 1

84

Answer 2

BAD is correct. It is 84. If you would like to use algebra, do the following:
x:= Unit Digit Number
y:= Tens Digit Number

The units digit is 4 less than the tens digit number so We know that
x=y-4

The tens digit is twice the units digit so we know that
y=2x

Now we can take the 1st equation and substitue into the second equation, then solve for Y.
y=2x
y=2(y-4)
y=2y-8
8=y so y=8
Now, sub this back into the 1st equation
x=y-4=8-4=4
so the number is yx = 84.