Answer:
Part 1) The linear equation is [tex]y=-4x+300[/tex]
Part 2) if he has 90 protein bars left, then 52.5 days have passed
Step-by-step explanation:
we know that
The linear equation in slope intercept form is equal to
[tex]y=mx+b[/tex]
where
y is the number of protein bars left
x is the number of days
m is the slope or unit rate
b is the y-intercept or initial value
In this problem we have
The slope is equal to
[tex]m=-4\ \frac{bars}{day}[/tex] ----> is negative because is a decreasing function
[tex]b=300\ protein\ bars[/tex]
substitute
[tex]y=-4x+300[/tex] ---> linear equation that represent this situation
If he has 90 protein bars left
so
For y=90
substitute in the linear equation and solve for x
[tex]90=-4x+300\\4x=300-90\\4x=210\\x=52.5\ days[/tex]
therefore
if he has 90 protein bars left, then 52.5 days have passed