3x + 5 = -7 describes the story about the temperature tripling and then rising 5 degrees since midnight, and finding the temperature at midnight.
7 = 3(5 + x) describes the story about Jada giving away 5 pink roses to each of her 3 favorite teachers, and finding how many white roses she gave away.
5(1/x) - 1/5 = 1/7 describes the story about a musical instrument company reducing the time it takes to build a guitar, and finding the amount by which they reduced the time.
(x + 7) = 5 describes the story about a club putting its members into 5 groups for an activity, and finding how many students were in each group after 7 students left early.
30% of 527 = x describes a story that is not provided in the prompt.