I think this is the answer + working out
x= Tori's age
y= her grandmother's age
x+y=72
5x=y
5x-y=0
x+y=72
+(5x-y=0)
6x=72
72 divided by 6=
x=12
So Tori is 12...
We substitute 12 for x into the first equation...
12+y=72
Bring 12 to the other side
y=72-12
y=60
Her grandmother is 60 and Tori is 12.