Finding base when you have part and rate

I feel so stupid, but I simply can't figure this out.

A. Current price is $359. This is a 15% increase from last year. What was the price last year?
B. Current price is $456. This is a 12% increase from last year. What was the price last year?
C. Current price is $34,800. This is a 13.4% increase. What was the price last year?

I know these will all use the same formula. I don't need the answers, just the formula to use. Thank you.

A. let p represent last year's price: 359 = 0.15p + p = 1.15p

p = 359/1.15

Got calculator?

The others are exactly the same question only with different numbers. Your calculator is going to get a workout!

just think of it like this

year 0: we had a certain amount of money, lets call it x.
year 1: we added 15% to it, so x + 0.15x
now we know that in year 1, our price is 359.

so we get x + 0.15x= 359, 1.15x= 359, divide both sides by 1.15 to get x alone,
so we get x= 359/1.15