The Robinson family and the Moore family are going on a day trip to visit the Square Caverns on Monday. The Robinson family has 2 parents and 4 children and paid $75
for admission. The Moore family has 2 parents and 3 children and paid $60. If x
represents the admission price of each parent and y represents the admission price of
each child, which is a system of equations that could be used to determine the
admission price of an adult ?