2x + 4y = 14
4x + y = 20......multiply by -4
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2x + 4y = 14
-16x - 4y = -80 (result of multiplying by -4)
---------------add
-14x = -66....as u can see, ur y's cancel out
so ur answer is : 1st answer choice <==
** and just so u know, u could have multiplied the 1st equation by -2, and it would have cancelled out ur x's
D is the answer because all you have to do is solve
About 7,460 punds if you add everything together
"He starts both trains at the same time. Train A returns to its starting point every 12 seconds and Train B returns to its starting point every 9 seconds". Basically, what you need to do is find the least common multiple. The least common multiple of 12 and 9 is 36, so the least amount of time, in seconds, that both trains will arrive at the starting points at the same time is 36 seconds.
