jessica is given $20 per week and also got $100 from her grandma for her birthday.If all of this money is put into her bank account, how long has she been saving if she has $320 ?
Let N be the number of weeks she has received the $20.
So we have
20N + 100 = 320 subtract 100 from each side
20N = 220 divide both sides by 20
N = 11 ...so, she has been saving for 11 weeks
