Question

How can we write an algebraic expression to describe a two-digit number whose unit's digit is 5 less than the ten's digit?

Answer 1

Let x= the ones digit

Then x+5=the tens digit

Hence the equation is: 10(x+5)+x=x+5+x+63

10(x+5)+x=x+5+x+63

10x+50+x=2x+68

11x+50=2x+68

-2x-50 -2x-50

---------------------

9x=18 Divide both sides of the equation by 9

x=2

Hence the number is 10(2+5)+2=10(7)+2=70+2=72.