Answer:
62
Step-by-step explanation:
average = [tex]\frac{totalscore}{count}[/tex]
Let x represent his fourth score, then
[tex]\frac{83+79+96+x}{4}[/tex] = 80, that is
[tex]\frac{258+x}{4}[/tex] = 80 ( multiply both sides by 4 )
258 + x = 320 ( subtract 258 from both sides )
x = 62
He must obtain a score of 62 in his fourth test