Together, Hal and Ula paint 30 square meters of a wall in
1 hour. Then they paint another
18 square meters, but Hal works
for 30 minutes while Ula works
for 45 minutes. Write and solve
a system of equations to find the
painting speed of each person,
in square meters per hour. Then
calculate how long it would take
Hal and Ula to paint 90 square
meters of wall together.