Assigning variable values to if statement

if GPA == unweighted:
A+ = 4.33
A = 4
A- = 3.67
B+ = 3.33
B = 3.0
value1 = credits*grade1

Ok so I am trying to assign those number values to those variables if the if statement is true, but when I run the program, it says there is a syntax error. Can someone please help me fix this? Thanks.