SOLUTION: A car travels 355 miles by going one speed for 3 hours and another speed for 4 hours. if it travels 3 hours at the second speed and 4 hours at the first speed, it would have gone 3

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Question 1049373: A car travels 355 miles by going one speed for 3 hours and another speed for 4 hours. if it travels 3 hours at the second speed and 4 hours at the first speed, it would have gone 345 miles. find the two speeds.
Found 2 solutions by jorel555, advanced_Learner:
Answer by jorel555(1290) About Me  (Show Source):
You can put this solution on YOUR website!
Let m be the first speed, and n be the second. Then:
3m+4n=355
4m+3n=345. So:
16m+12n=1380
9m+12n=1065
7m=315
m=45 mph
n=55 mph. ☺☺☺☺

Answer by advanced_Learner(501) About Me  (Show Source):
You can put this solution on YOUR website!
the equations are
355=3x%2B4y
345=4x%2B3y
Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
+system%28+%0D%0A++++3%5Cx+%2B+4%5Cy+=+355%2C%0D%0A++++4%5Cx+%2B+3%5Cy+=+345+%29%0D%0A++We'll use substitution. After moving 4*y to the right, we get:
3%2Ax+=+355+-+4%2Ay, or x+=+355%2F3+-+4%2Ay%2F3. Substitute that
into another equation:
4%2A%28355%2F3+-+4%2Ay%2F3%29+%2B+3%5Cy+=+345 and simplify: So, we know that y=55. Since x+=+355%2F3+-+4%2Ay%2F3, x=45.

Answer: system%28+x=45%2C+y=55+%29.