On a man's tombstone, it is said that one sixth of his life was spent in childhood and one twelfth as a teenager. One seventh of his life passed between the time he became an adult and the time he married; five years later, his son was born. Alas, the son died four years before he did. He lived to be twice as old as his son did. How old did the man live to be?
x = x/6 + x/12 + x/7 + 5 + x/2 + 4
x = 14x/84 + 7x/84 + 12x/84 + 42x/84 + 9
x = 75x/84 + 9
84x/84 - 75x/84 = 9
9x/84 = 9
x/84 = 1
x = 84
x = 14x/84 + 7x/84 + 12x/84 + 42x/84 + 9
x = 75x/84 + 9
84x/84 - 75x/84 = 9
9x/84 = 9
x/84 = 1
x = 84
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. Two trains
travel toward each other on the same track, beginning 100 miles apart. One
train travels at 40
miles per hour; the other travels at 60 miles an hour. A bird starts flight at the same location as the faster train,
flying at a speed of 90 miles per hour. When it reaches the slower train, it turns around, flying the other
direction at the same speed. When it reaches the faster train again, it turns around -- and so on.
When the trains collide?
miles per hour; the other travels at 60 miles an hour. A bird starts flight at the same location as the faster train,
flying at a speed of 90 miles per hour. When it reaches the slower train, it turns around, flying the other
direction at the same speed. When it reaches the faster train again, it turns around -- and so on.
When the trains collide?
Ignore the bird bcoz bird is not affecting train's speed or direction. So, in 1 hr,both trains will collide as slower train will travel 40 miles and another train 60 miles in one hr. so, they ll collide after 1 hr.
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