Answer:
91
Step-by-step explanation:
Mean is calculated as
mean = [tex]\frac{sum}{count}[/tex]
let x be his test score of his last test , then
[tex]\frac{86+70+72+100+96+80+x}{7}[/tex] = 85 ( multiply both sides by 7 )
504 + x = 595 ( subtract 504 from both sides )
x = 91
