Question 84151
Solve algebraically using one variable: The first digit in a four digit number is four more than the second and the second is three less than the third. The fourth digit is one less than the third and the sum of the four digits is 21. What is the number? (HINT: first decide which digit you should call 'x'.)
LET III DIGIT = X
II DIGIT = X-3
I DIGIT =X-3+4=X+1
IV DIGIT = X-1
SUM OF ALL DIGITS =X+X-3+X+1+X-1=21
4X=24
X=6
HENCE THE NUMBER IS 
7365