It's urgent if someone can solve it and give an explanation I will give 100 points, thanks guys

What is the difference between the predicted value and the actual value

Which expression converts 45 degree to radians

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )