Colin is painting figurines. he spends 20 minutes painting each figurine. after painting for 60 minutes, he still has more figurines left to paint.

the number of f of figurines left to paint is a function of t, the amount of time in minutes colin spends painting.

write the functions formula.

f=-1/20t+12
[hints]
the rate at which colin paints is constant, so we're dealing with a linear relationship.

we could write the desired formula in slope-intercept form: f=mt+b. in this form, m gives us the slope of the graph of the function and b gives us the y-intercept. our goal is to find the values of m and b and substitute them into this formula.

we know that the number of figurines left for colin to paint decreases by 1 every 20 minutes, so the slope m is -1/20, and our function looks like f=-1/20t+b.

we also know that colin has 9 figurines left to paint after painting for 60 minutes, which means that when t=60, f=9. we can substitute this into the formula of the function to find b:

-1/20×60+b=9

-3+b=9

b=12

this means colin initially had 12 figurines to paint.

since m=-1/20 and b=12, the desired formula is:

f=-1/20t+12