Answer:
Part a) The linear model is 
Part b) The amount earned is 
Step-by-step explanation:
Let
x ----> total meals worth served by Sam in a month
y ----> total earned by Sam in a month
we know that
The total earned by Sam in a month is equal to the base salary plus the total meals worth served by Sam in a month multiplied by the tips averaging in decimal form
Tips average =15%=15/100=0.15
so

This is a linear equation in slope intercept form

where
m is the slope or the unit rate
b is the y-intercept or initial value
The slope of unit rate is equal to

The y-intercept or b is equal to

For x=6,000
substitute in the linear equation

