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Aladder 20m long leans against a wall is 15m high


  • Réponse publiée par: nila93
    Jose ncounter 30 passengers in the bus
  • Réponse publiée par: 09330399672

    let's start by listing all the givens.

    total distance is 420 miles.

    slower train goes at 45 mph

    faster train goes at 60 mph.

    the formula for distance is d=rt.

    the faster train's rate is 60 mph. we don't know how much distance that train will cover, therefore, we should give it a variable, such as d (any letter)the slower train's rate is 45 mph. obviously, it will cover much less distance than the faster train. so we can write it as 420 - d (the variable here should match the one above.we don't know the time it will consume for both of the trains so we can give it a variable like t.

    let's look at the given for the faster train. d (distance, unknown), 60 (rate), and t (time, unknown). using the formula d=rt. we can substitute 60 to the rate to make it d=60t. sure you might not able to solve it at hindsight, but we could substitute it to the slower train's equation.

    now, the equation for the slower train is 420 - d = 45t (420 - d is the distance, 45 is the rate, and t is the time.)

    substute 60t to d: 420 - 60t = 45tbring 60t to the other side by means of adding 60t to both sides: 420 - 60t+(60t) = 45t+(60t) ==> 420t=105tdivide 105 to both sides to isolate t: \frac{450}{105} = \frac{105t}{105}4 = t

    so if t = 4, it means the trains must travel 4 hours (because of miles per hour) before they meet

  • Réponse publiée par: axelamat70

    solution: a submarine was 250 m below sea level. it rose 75 m

  • Réponse publiée par: brianneaudreyvuy
    Blah blah blah is the way you answer someone who talks so much without any sense.
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Aladder 20m long leans against a wall is 15m high...