As part of a new fitness plan, sabir walks on a treadmill at the same speed for 15 minuets every morning. the table shows the calories he burns over time

The relationship between Sabir and calories he burns can be modeled using a linear function given by:
y=ax+b
where
a=slope
b=y-intercept
from the graph, the slope will be given as follows:
taking points (3,15) and (12,60)
a=(60-15)/(12-3)=5 calories/minute
thus using the slope and a point (3,15) the equation will be:
a(x1-x)=(y1-y)
plugging the values we obtain:
5(x-3)=y-15
5x-15=y-15
thus
y=5x
thus the equation is:
y=5x