Question 81569
x=one number
y=the other number
sum=to add
difference=to subtract
.
x+y=35
x-y=12
.
One method you can use is subtraction;
x+y=35
x-y=12
_______
2x-0y=47
.
2x=47
x=47/2
.
So, x=47/2=23.5
x+y=35
23.5+y=35
y=35-23.5
y=11.5
checking:  23.5+11.5=35
.
Plug the values into the second equation:
x-y=12
23.5-11.5=12 [checks out]