It will take 133 days for Janet to save the money.
In order to find this, start by finding out how much more she needs to save. To find this, subtract the amount she has from the total goal amount.
500-120 = 380
So we know that she needs $380. To find how many weeks that it, divide the total amount needed to save by the amount she can save a week.
380/20 = 19 weeks.
Now to find the number of days, multiply the weeks by the number of days in a week.
19 x 7 = 133 days