15. Matthew and some friends are going to a concert. They hire a car service for $60 to
drive them to a restaurant for dinner and then to the concert. They divide the $75 cost
of the dinner equally. However, since Matthew's dad provided concert tickets for the
group, the friends agree that Matthew doesn't have to help pay for the car service.
The friends divide this cost equally among themselves. If each friend spends a total of
$30, how many friends went to the concert with Matthew?
A4
B5
C6
D7