(-48)-[18-{(-16)-(5-(4-7))}]

−48−[18−((−16)−(5−(4−7)))]

⇒ −48−[−18((−16)−(5−(−3)))]

⇒ −48[18−(−16)−8)]

⇒ −48[18−(−24)]

⇒ −48−(18+24)

⇒ −48−42

⇒ −90

answer: 12   they all have at least 28 days

step-by-step explanation: haha

- (2, -7)

- lines r and s and lines t and u must be parallel