What is linear equation???

an equation between two variables that gives a straight line when plotted on a graph. In mathematics, a linear equation is an equation that may be put in the form {\displaystyle a_{1}x_{1}+\cdots +a_{n}x_{n}+b=0, } where x_{1}, \ldots, x_{n} are the variables, and {\displaystyle b, a_{1}, \ldots, a_{n}} are the coefficients, which are often real numbers.

its a straight line parallel to the time axis

9 sandwiches per hour

step-by-step explanation:

when we have a rate, we want a 1 in the denominator

27/3 = 9

27 sandwiches/ 3 hours = 9 sandwiches/hour