Math
posted by Nicholas .
i am a four digit number. all of my digits are different. my first digit is twice my fourth digit. my second digit is twice my first digit.my last digit is twice my third digit. the sum of my digits is 15. what number am i?

Let the fourth digit be x
First digit = 2x
Second digit = 2(2x) = 4x
Third digit = x/2
Thus x+2x+4x+x/2 = 15
15x/2=15
x=2
Thus the number is (2*2)(4*2)(2/2)(2)
= 4812 
a four digit number equals the sum of twice of its reversed and half of it. also its first digit is 4 times the last digit and second digits is 7 times the 3rd digit .the sum of four digits of the number is ?

I am a four digit number with 6 hundreds and 5 ones .the sum of all my digits is 15 what am I.