SOLUTION: tina has 20 coins in dimes and quarters. their total value is $3.20. how many coins of each type does she have?

Algebra ->  Customizable Word Problem Solvers  -> Coins -> SOLUTION: tina has 20 coins in dimes and quarters. their total value is $3.20. how many coins of each type does she have?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 827008: tina has 20 coins in dimes and quarters. their total value is $3.20. how many coins of each type does she have?
Answer by TimothyLamb(4379) About Me  (Show Source):
You can put this solution on YOUR website!
---
x = dimes
y = quarters
---
x + y = 20
10x + 25y = 320
---
copy and paste the above linear system in standard form into this matrix-method solver:
https://sooeet.com/math/system-of-linear-equations-solver.php
---
solution:
x = dimes = 12
y = quarters = 8
---
system matrix
1 1
10 25
---
inverse of system matrix
1.6666667 -0.066666667
-0.66666667 0.066666667
---
determinant of system matrix = 15
---
Solve and graph linear equations:
https://sooeet.com/math/linear-equation-solver.php
---
Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
---
Solve systems of linear equations up to 6-equations 6-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php