He needs to walk 63,000 steps in a week because 7 x 9,000 = <<7*9000=63000>>63,000
He has 18,100 steps to walk on Friday and Saturday because 63,000 - 9,400 - 9,100 - 8,300 - 9,200 - 8,900 = <<63000-9400-9100-8300-9200-8900=18100>>18,100
He needs to walk an average of 9,050 on Friday and Saturday because 18,100 / 2 = <<18100/2=9050>>9,050
#### 9,050