A teacher purchased 300 colored pencils for an upcoming project. The pencils she ordered come in packs of 20 and packs of 30. She ordered 14 packs in all. Write a system of equations to find the number of 20-pencil packs (x) and 30-pencil packs (y) the art teacher ordered.
Q. A teacher purchased 300 colored pencils for an upcoming project. The pencils she ordered come in packs of 20 and packs of 30. She ordered 14 packs in all. Write a system of equations to find the number of 20-pencil packs (x) and 30-pencil packs (y) the art teacher ordered.
Define Variables and Equations: Define the variables and write the equations based on the given information.The teacher ordered a total of 14 packs, which can be represented by the equation:x+y=14This equation represents the total number of packs ordered.
Write Total Pencils Equation: Write the second equation based on the total number of pencils.The teacher ordered 300 colored pencils in total. Since packs come in 20s and 30s, we can represent this with the equation:20x+30y=300This equation represents the total number of pencils ordered.
Solve Using Elimination: Solve the system of equations using substitution or elimination.We can use the elimination method by multiplying the first equation by −20 to eliminate x:−20(x+y)=−20(14)−20x−20y=−280Now we have the system:−20x−20y=−28020x+30y=300
Add Equations to Eliminate x: Add the two equations together to eliminate x.(−20x−20y)+(20x+30y)=−280+300The x terms cancel out, and we are left with:10y=20
Solve for y: Solve for y.Divide both sides of the equation by 10 to find the value of y:1010y=1020y=2This means the teacher ordered 2 packs of 30-pencil packs.
Substitute to Find x: Substitute the value of y back into one of the original equations to solve for x. Using the first equation: x+y=14x+2=14 Subtract 2 from both sides to solve for x: x=14−2x=12 This means the teacher ordered 12 packs of 20-pencil packs.
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