There is a simple way to approach this problem:
First - write down all your given values
Second - reason it out in words, put down stuff you already know that might be related
Third - solve!
First: Given Values
The total amount needed to be saved: $674.72
Total time: 1 year
Estimated savings per month: $40.00
Second: What do I already know?
If there's one year then I know there are 12 months in that year. They told me I'm saving $40.00/month so I should probably find out how much I'm saving in 1 year if I save $40.00/month. I can do that by multiplying ($40.00/month)(12 months)
($40/month)*(12 months) = $480/ year
This is a reasonable but inaccurate estimate since it's close but not close enough to what she actually needs to save. If she wants to save $674.72 in 12 months then we can find that amount by dividing the total amount into 12 pieces (each piece is a month) which gives us the amount required in 1 piece which is representative of 1 month.
So ($674.72) / (12 months) = $56.23/ month, rounded to the nearest hundredth of a decimal place.