Question 924002
Let 100x+10y+0 be the number
We are told that:
x+y=12---eq1
We are also told that:
100y+10x+0=100x+10y+0+540
90x-90y=-540
x-y=-6---------eq2

add eq1 and eq2
2x=6
x=3------ the 100s digit
substitute x=3 in eq2:
3-y=-6
y=9 -----the 10s digit
Sooo the original number is 390

CK
3+9=12
12=12
930=390+540
930=930

Hope this helps----ptaylor