Hello, magentarita!
I assume your mother's name is Anna . . .
In 7 years, I will be half Anna's age.
Thirteen years ago, she was 6 times as old as I was then.
How old is Anna now?
Let = my age (now).
Let = Anna's age (now).
Seven years from now, both of us are 7 years older.
. .
. .
We have: .
Thirteen years ago, both of us were 13 years younger.
. .
. .
We have: .
Subtract [2] from [1]: .
Substitute into [1]: .
Therefore, Anna is 43 years old.