First, you have to substitute for x, which would make the problem f(x)=7.45(-4.3)+33.7
Now, you just have to use the PEMDAS method (Parenthesis, Exponents, Multiplication, Division, Addition, Subtraction)
f(x)= -32.035+33.7
f(x)=1.665
To rewrite something as a decimal, simply divide the numerator and denominator.
-33 / 25 = -1.32
So -33/25 = -1.32
Price after 9% increased 1800
Price before increase 1800-9%*1800
=1638