<PRE><B>Question 977943</B>
x is the tens digit
y is the ones digit

10x+y is the number and 10y+x is the reverse

10x+y-36=10y+x
9x-36=9y
9x=9y+36
x=y+4

x+y=8
y+4+y=8 by substitution
2y=4
y=2
x=6

62-36=26
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120 mph average on the way there, which is x+y
60 mph average on the way back, which is x-y
x+y=120
x-y=60
2x=180
x=90 mph of plane in still air
y=30 mph of wind

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