2015 AMC 10A Problems/Problem 2: Difference between revisions
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==Solution 3== | ==Solution 3== | ||
Let x be the number of square tiles. A square has <math>4</math> edges, so the total number of edges from the square tiles is <math>4x</math>. There are <math>25</math> total tiles, which means that there are <math>25-x</math> triangle tiles. A triangle has <math>3</math> edges, so the total number of edges from the triangle tiles is <math>3(25-x)</math>. Together, the total number of tiles is <math>4x+3(25-x)=84</math>. Solving our equation, we get that <math>x=9</math> which means that our answer is <math>\boxed{\textbf{(D) }9}</math>. | |||
==Video Solution== | ==Video Solution== | ||
Revision as of 21:37, 10 January 2021
Problem
A box contains a collection of triangular and square tiles. There are 
tiles in the box, containing 
edges total. How many square tiles are there in the box?
Solution
Let 
be the amount of triangular tiles and 
be the amount of square tiles.
Triangles have 
edges and squares have 
edges, so we have a system of equations.
We have 
tiles total, so 
.
We have 
edges total, so 
.
Multiplying the first equation by on both sides gives 
.
Second equation minus the first equation gives 
, so the answer is 
.
Solution 2
If all of the tiles were triangles, there would be 
edges. This is not enough, so there need to be some squares. Trading a triangle for a square results in one additional edge each time, so we must trade out 
triangles for squares. Answer:
Solution 3
Let x be the number of square tiles. A square has edges, so the total number of edges from the square tiles is 
. There are total tiles, which means that there are 
triangle tiles. A triangle has edges, so the total number of edges from the triangle tiles is 
. Together, the total number of tiles is 
. Solving our equation, we get that 
which means that our answer is .
Video Solution
~savannahsolver
See Also
| 2015 AMC 10A (Problems • Answer Key • Resources) | ||
| Preceded by Problem 1 |
Followed by Problem 3 | |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
| All AMC 10 Problems and Solutions | ||
These problems are copyrighted © by the Mathematical Association of America. 
