If we let p and t be the masses of the paper and textbook, respectively, the equations that would best represent the given in this item are:
(1) 20p + 9t = 44.4
(2) (20 + 5)p + (9 + 1)t = 51
The values of p and t from the equation are 0.6 and 3.6, respectively. Thus, each paperback weighs 0.6 pounds and each textbook weighs 3.6 pounds.
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If this is what you mean..?
In order to do this you would work backward from the answer.
You have x = 25 and ant to include and addition. As we are working backwards, we use the opposite operation to addition - subtraction. We'll make it an easy number so we will subtract 15 to get to 10.
So far it looks like 10 = 15 + x
Now, to include a division, we want to do the opposite again, multiplication. Pick any number to multiply 10 by - for this example we'll choose 7.
7 x 10 = 70
Now we can write out the equation -
70/7 + 15 = x
No brackets are required as Division comes before addition in BIDMAS.
An alternate choice would be to have x the other side of the '='
To do this, multiply x by a number of choice (for example 3) to make the divison section of the equation. This makes 75. This can be written as a fraction. 75/x = 3
Next, for the addition, whatever happens on one side, the exact same happens on the other. Pick any number to add on (e.g. 5) and re-write the equation.
75/x + 5 = 8
Sorry if this doesn't make perfect sense
Answer:
The speed in still water is 5 miles per hour.
Step-by-step explanation:
distance with current = 90 miles
distance against current = 10 miles
speed in still water = s
speed of current = 4 mph
speed with current = s + 4
speed against current = s - 4
time = t
speed = distance/time
distance = speed * time
With current:
90 = (s + 4) * t
Against the current:
10 = (s - 4) * t
We have a system of equations:
90 = (s + 4) * t
10 = (s - 4) * t
90 = ts + 4t
10 = ts - 4t
Subtract the second equation from the first equation.
80 = 8t
10 = t
t = 10
10 = t(s - 4)
10 = 10(s - 4)
1 = s - 4
s = 5
Answer: The speed in still water is 5 miles per hour.
