So a woman deposit $100 for his Son’s first birthday, then added 125$ on his second birthday and 150$ on his 3rd birthday.
We need to find the amount she deposit on her son’s 17 birthday.
And then the total amount she deposit in all.
Notice that every year her deposit increase into 25$
=> $100 + 25x (where x is the number of his son’s age)
=> 100 + 25(16) additional 16 years to get 17
=> 100 + 400
=> $500
Thus, on his 17th birthday, a woman deposit $400 and he got $500 in all.