need help wirh this problem

i need script for this if some one can help me
user must enter values for a b c d e

a 0
b 0
c 0
d 0
e 0

Sub Total 0
Tax 0
Total 0


subtotal= a*2*0.49+b*33*c+d*1*c+e*65+a/60*10*b
tax= subtotal*0.7
total= subtotal+tax