The total if all 236 coins were nickels would be $11.80, which is $3.95 short of the actual amount.
Replacing a nickel with a dime adds $0.05 to the total value, so there must have been $3.95/$0.05 = 79 such replacements.
There are 79 dimes.
There are 236 -79 = 157 nickels.
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Using the given variables, the problem statement gives rise to two equations. One is the based on the number of coins. The other is based on their value.
- n + d = 236
- .05n +.10d = 15.75
Solving the first for n, we get
... n = 236 - d
Substituting that into the second equation, we have
... .05(236 -d) +.10d = 15.75
... .05d = 15.75 -236·.05 . . . . . collect terms, subtract .05·236
... d = 3.95/.05 . . . . . . . . . . . . . divide by .05
... d = 79
... n = 236-79 = 157
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The solution should look familiar, as it matches the verbal description at the beginning.
They flowed 15 miles UP.
This is equivalent to a positive 15.
Then 9 miles DOWN.
This is equivalent to a negative 9.
Now put these two numbers together.
15-9
So, c. 15-9=6
That’s easy just place 2.4 on top of 1.5 and do the math, I did it in the picture for you, since there are two decimal points one in 2.4 and the second in 1.5. So the answer is 3.60 as shown in the pic. Any questions ? Sorry the picture is sort of messed
