SOLUTION: Multistep word problems Word problems are more complicated with two or more unknown values. First, assign a variable to each unknown value. The word problem should then be trans

Question 309544: Multistep word problems
Word problems are more complicated with two or more unknown values. First, assign a variable to each unknown value. The word problem should then be translated into the appropriate number of mathematical equations, which can then be solved by substitution. Keep in mind that the number of mathematical equations needed is equal to the number of variables.
Consider the following multistep word problem:
The sum of the ages of a brother and sister is 25. If four times the brother's age is subtracted from three times the sister's age, the difference is 5.Consider just the first sentence of this multistep word problem.
Sentence 1: The sum of the ages of a brother and sister is 25.
Give an equation that represents this statement using as the age of the brother and as the age of the sister
??????If four times the brother's age is subtracted from three times the sister's age, the difference is 5.Give an equation that represents this statement using b as the age of the brother and s as the age of the sister.

Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
The sum of the ages of a brother and sister is 25. If four times the brother's age is subtracted from three times the sister's age, the difference is 5.Consider just the first sentence of this multi-step word problem.
:
Let b = brother's present age
Let s = sister's present age
:
Sentence 1: The sum of the ages of a brother and sister is 25.
Give an equation that represents this statement using as the age of the brother and as the age of the sister
b + s = 25
:
If four times the brother's age is subtracted from three times the sister's age, the difference is 5.
Give an equation that represents this statement using b as the age of the brother and s as the age of the sister.
3s - 4b = 5
:
Substitution is one way to solve this, rearrange the 1st equation to:
b = (25-s)
:
Substitute (25-s) for b in the 2nd equation
3s - 4(25-s) = 5
3s - 100 + 4s = 5
3s + 4s = 5 + 100
7s = 105
s =
s = 15 yrs is sister's age
then using the equation b = 25-s:
b = 25 - 15
b = 10 yrs is brothers age
;
:
Confirm the solution in the 2nd statement;
"four times the brother's age is subtracted from three times the sister's age, the difference is 5."
3(15) - 4(10) = 5
:
Do you understand this now???
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