+0  
 
0
99
1
avatar

Find the cost of a pencil and eraser if two pencils and three erasers cost 140 dollars, and fivepencils and four erasers cost 280 dollars.​

 Mar 16, 2021
 #1
avatar+73 
0

let's define a variable for pencils and for erasers.

 

now we can set up a sysem of equations.

 

2p + 3e = 140

and

5p + 4e = 280

 

for this problem, i'm going to use elimination.

 

we multiplfy the first equation by 5 and the second equation by 2.

 

10p + 15e = 700

10p + 8e = 560

 

notice how we now have a 10p on both equations. we can subtract the two equations to cancel those out.

 

7e = 700 - 560

7e = 140

e = 20

 

now we can solve for p.

 

2p + 3(20) = 140

2p + 60 = 140

2p = 80

p = 40

 

hope this helped! please let me know if you are confused about anything i did smiley

 Mar 16, 2021

24 Online Users

avatar