math
posted by Dee on .
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?

84

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=y4
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(y4)
y=2y8
8=y so y=8
Now, sub this back into the 1st equation
x=y4=84=4
so the number is yx = 84.