I'm not sure how to set this problem up and would like to see how it's done. Thanks!
If 5 times A's salary exceeds twice B's by $6400, and 4 times A's salary exceeds 3 times B's by $2600, find the salary of each man and show work.
2 Answers
Sometimes it is easiest to write the words of the problem using math symbols to find the equation you are being asked to solve:
5A = 2B + $6400 and 4A = 3B + $2600
You need to use one equation and get one variable alone. I chose the one in bold.
4A = 3B + $2600 (divide both sides by 4)
4 4
A = 3/4 B + $650 (Now you have solved for A. Use this in the other equation for A.)
5(3/4 B + $650) = 2B + $6400 (You must multiply A by 5 before you continue.)
15/4 B + $3250 = 2B + $6400 ( Solve for B by moving all B's to one side. Also, 15/4 = 3 3/4)
-2B -2B
(3 3/4 B + $3250 = 2B + $6400)
-2B -2B
1 3/4 B + $3250 = $6400
-$3250 -$3250
1 3/4 B = $3150
B = $1800 (Enter this into A = 3/4 B + $650)
A = 3/4 ($1800) + $650
A= $2000
Mitchell,
We need to translate the words in this problem into some form of equation:
If 5 times A's salary= 5*A or 5A
exceeds twice B's by 6400= is more than 2B by 6400= 2B+6400
So, 5A= 2B+6400
Then, we set up another equation:
4 times A's salary= 4A
exceeds 3 times B's salary by 2600= 3B+2600
So, 4A=3B+2600
Now we have a system of equations.
5A= 2B + 6400
4A= 3B + 2600
If we multiply the first equation by -3 and the second by 2 we get:
-15A= -6B - 19200
8A= 6B + 5200
So the B's will cancel.
Then we add them together:
-7A = -14000
A= 2000
Then plug A back into the first equation:
5(2000)= 2B + 6400
10000= 2B + 6400
2B=3600
B= 1800
Then you would check to make sure the answers made sense in the problem.
Good luck!







Comments
You're very welcome Courtnee! I'm glad that you understand it now :D
- Shannon M. 3/2/2013