Laurie is trying to stay within 10 feet of her current diving depth of –30 feet (with regard to sea level) so that the light is still good but she can be close to the sea life during her scuba dive. Which two equations can be used to find the minimum and maximum depths Laurie wants to stay between?
Answer
A
-30 - x = 10 and -30 - x = –10
B
-30 + x = 10 and -30 + x = –10
C
x + 10 = 30 and x + 10 = –30
D
x – 10 = 30 and x – 10 = –30
Explanation
A depth within 10 feet of −30 feet is 10 feet above or below −30. The boundary depths are −30 + 10 = −20 feet and −30 − 10 = −40 feet. Choice A’s equations, −30 − x = 10 and −30 − x = −10, give those two depths when solved.
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