What is the change of entropy for a heat engine using 500.0j at 20.0c

1.71 J/K 
hope it helps :D!!

Ibelieve a is the correct answer because 3 is the y-intercept you can see it from the graph. so from here the answers could only be a and c. they are differently at the sign.substitute x with 1so the equation for a is 3*(1.4)^x3*(1.4)^1 = 4.2look back at the graph it is true that when x= 1 y= 4.2if you use equation from c. when x= 1 then y will be negative number which is falseso correct answer is a