Question 97981
let x=grade he has to get on the final.
68*.2+78*.2+88*.2+.4x=80
13.6+15.6+17.6+.4x=80
46.8+.4x=80
.4x=33.2
x=33.2/.4=83
Check:
46.8+83*.4=46.8+33.2=80
Ed