Answer:
C
Explanation:
So lets look at the first equation.
This would represent 60-15=x
This is because 60 shells minus 15 shells she gave away.
Next is B, whihc is also 60-15=x
This is because Mr yungs brother is 60 years old and mr yung is 15 years younger.
Next is c, whihc is 60+15=x
This is because they had 60, gave 15 already, and want to find out what they started with.
FInally we are left with d.
This is 15+x=60
Well...none of those look like x-15=60
But lets go back to c:
60+15=x
Lets try to rwwrite this.
Subtract 15 from both sides, and you get:
60=x-15
Just make this proper by putting the x-15 before the 60:
x-15=60
That looks like x-15=60
Now we know our answer!
C
Hope this helps ;)