Denise G. answered 01/15/20
Algebra, College Algebra, Prealgebra, Precalculus, GED, ASVAB Tutor
Start with defining the variables.
Let x=the 1st digit
Let y=the 2nd digit
Sum means addition, difference is subtraction. So the 2 equations are:
x+y=12
x-y=6
To do this using elimination, add the equations together. The y and -y will add to zero, so this cancels out. The resulting equation after you add them together is
x+x=12+6 Simplify
2x=18 Divide bother sides by 2 and simplify
2x/2=18/2
x=9
You can use either equation to solve for y next. I will use the first one.
x+y=12 Plug in x=9
9+y=12 Subtract 9 from both sides and simplify
9+y-9=12-9
y=3
The 2 digit number is 93.