Edward A. answered • 01/22/20

Math Tutor, Retired Computer Scientist and Technical Communicator

Sarah, it’s interesting that 8 and 10 **also** qualify.

if the second step had been translated using 2 as the difference (that is, (x+2)-x), then the equation would have been

2X+2 = 18

x = 8, x+2 = 10

so there are two sets of answers, both correct.