Answer:
One pound of jelly beans costs $3.75.
One pound of trail mix costs $1.75.
Step-by-step explanation:
Let [tex]x[/tex] be equal to one pound of jelly beans.
Let [tex]y[/tex] be equal to one pound of trail mix.
1) Form equations
We're given:
7 pounds of jelly beans + 9 pounds of trail mix = $42
⇒ [tex]7x+9y=42[/tex]
5 pounds of jelly beans + 3 pounds of trail mix = $24
⇒ [tex]5x+3y=24[/tex]
Now, we have our two equations:
[tex]\displaystyle\left \{ {{7x+9y=42} \atop {5x+3y=24}} \right.[/tex]
2) Solve for x using elimination
[tex]\displaystyle\left \{ {{7x+9y=42} \atop {5x+3y=24}} \right.[/tex]
Multiply the second equation by 3 to change 3y to 9y:
[tex]5x+3y=24\\3(5x+3y)=3(24)\\15x+9y=72[/tex]
Subtract the first equation from the second to eliminate y:
[tex]15x+9y=72\\- 7x+9y=42\\\rule{2.5cm}{0.4pt}\\8x=30[/tex]
Divide both sides by 8 to isolate x:
[tex]\displaystyle x=\frac{30}{8} \\\\x=3.75[/tex]
Therefore, one pound of jelly beans costs $3.75.
2) Solve for y using substitution
[tex]\displaystyle\left \{ {{7x+9y=42} \atop {5x+3y=24}} \right.[/tex]
Now, we know that x=3.75. Plug this value into one of the equations and solve for y:
[tex]5x+3y=24\\5(3.75)+3y=24\\18.75+3y=24\\3y=24-18.75\\3y=5.25\\\\\displaystyley=\frac{5.25}{3} \\\\y=1.75[/tex]
Therefore, one pound of trail mix costs $1.75.
I hope this helps!
