Question 1084551
x+y=143
x-y=7
2x=150
x=75
y=68
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P(pen or pencil)=P(pen)+p(pencil)-p(both pen and pencil)
or=5+4-2=7 (the minus two is the double counting)
7 contain one or the other
therefore 3 don't contain any.
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at 100km/h average speed*3 hours is 300 km distance
to do it in 2 hours requires 300 km/2 hr  or 150 km/hr.