Mary, don't be discouraged at this. Just draw strength. You can do this, and you will do better the next time.
When I wanted to go back and get a teacher's certificate I had been out of school about 7 years, and I had not done any math for at least 10 years. I have a BA in psychology, but I had gone through calculus, so was well versed in math. But here's the challenge--what you don't use gets pretty rusty.
I had to take an entrance exam to get into an accelerated teaching program. Guess what, I had difficulty with math, too. I remember sitting at the exam looking at a square root sign with a little three next to the symbol and wondering "what's that?" It took me almost a minute to remember that it was asking for the root of a cubed number. Precious time wasted. So I didn't do too well on math either, and had to brush up.
But I did eventually get through the required credits, get my teaching certificate and teach for several years.
Mary, it's pretty normal to have to brush up on math. Just encourage yourself and go on. You can do this!