Wilda can do the job in 4 hours ... she does 1/4 (or 0.25) of it each hour.
Karla can do it in 5 hours ... she does 1/5 (or 0.2) of it each hour.
Wilda worked alone for 1 hour ... 0.25 of the job was done before her helper
arrived. So only 0.75 of the job remained to be done together.
Working together, they accomplish (0.25 + 0.2) = 0.45 of the job in 1 hour.
How many times do they need to do 0.45 of the job in order to finish
the 0.75 of it that remains ? That's the number of hours it will take them,
working together.
0.75 / 0.45 = <em>1 and 2/3</em>
After Wilda worked alone for 1 hour and Karla came along to join her, it will
take them another <em>1 hour and 40 minutes</em> to finish the job and go for a swim.
For this case we must algebraically rewrite the given expression. So:
x: It is the variable that represents an unknown number
"double a number" is represented as: 
"6 less than double a number" is represented as: 
So, the final expression is: 
If we want to rewrite the expression in an equivalent way, we take common factor 2:

Asnwer:

Equivalent expression: 
Step-by-step explanation:
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Answer:
<em>x</em>/4
Step-by-step explanation:
7/8x-5/8x fractional coefficients = x/4
North American : South American : European
9 : 5 : 2
Multiply all by 10
90 : 50 : 20
The answer is 50 South American butterflies.