Let y be the tiles that is done in x days. So first calculate the slope of the line
At ( 1, 5) and ( 4, 35)
M =( 35 – 5) / ( 4 – 1)
M = 10
Then solve the y intercept
Y = mx + b
5 = 10(1) + b
B = -5
Y = 10x – 5
100 = 10x -5
X = 10.5 days to finish tiling 100 tiles