Answer:
Part 1) Michael earned walking dogs $45
Part 2) Michael earned all together $87
Step-by-step explanation:
Part 1) How much money did Michael earn walking dogs?
Let
x ----> money earned mowing lawns
y ---> money earned washing windows
z ---> money earned walking dogs
we know that
x=$27
y=x-12-----------> y=27-12=$15
z=3y ---> z=3*15=$45
Part 2) How much did earn all together?
Adds the amount that Michael earned mowing lawns plus the amount that earned washing windows plus the amount that earned walking dogs
so
x+y+z
x+y+z=27+15+45=$87