4 hours
Step-by-step explanation:
we have to make an equation out of the points given, so the slope is change in y / change in x = 85-80/2-1 = 5 (I used the points 1,80 and 2,85 to find this but it would be the same no matter what two points you took).
then we need to find the y intercept.
we are making it into y=mx+b. m is 5 (the slope) and b is the y intercept.
we find this by plugging the slope into a random point on the chart.
85 = (5)(2) + b
b=75
y=5x+75
to get a 97:
97=5x+75
22=5x
x=22/5 or 4.4 hours, so I'd guesstimate 4 hours
