Answer:
143.75X = Y
Step-by-step explanation:
Since I had to hire a plumber to come fix a leaky pipe, and the first day he worked 3 hours and charged me $ 450, while the next day he came back and finished the job working another 5 hours charging me $ 700, to find the equation that represents the cost, and, after x hours of working, the following calculation must be performed: 
 
(450 + 700) / (3 + 5) = Y 
1150/8 = Y 
143.75 = Y 
 
Thus, the hourly cost of the plumber's work was $ 143.75.