GivenGiven a two digit number #ab# with the digit sum #a+b=7#, and the difference of #ab# and #ba# equal to nine, find a and b? a digit number #ab# with the digit sum of 7 and the differ

1 Answer
Jun 26, 2017

The answer is #a=4# and #b=3#

Explanation:

A number with 2 digits #ab# can be written as #(10a+b)#

Therefore,

#ab-ba=9#, is

#10a+b-10b-a=9#

#9a-9b=9#

#a-b=1#

But we have, also

#a+b=7#

Therefore,

#2a=8#

#a=4#

and

#b=3#