One roll of plain costs $20 and one roll of shiny costs $20 also.
Step-by-step explanation:
Let,
Cost of one roll of plain = x
Cost of one roll of shiny = y
According to given statement;
2x+2y=80 Eqn 1
8x+10y=360 Eqn 2
Multiplying Eqn 1 by 4
[tex]4(2x+2y=80)\\8x+8y=320\ \ \ Eqn\ 3[/tex]
Subtracting Eqn 3 from Eqn 2
[tex](8x+10y)-(8x+8y)=360-320\\8x+10y-8x-8y=40\\2y=40[/tex]
Dividing both sides by 2
[tex]\frac{2y}{2}=\frac{40}{2}\\y=20[/tex]
Putting y=20 in Eqn 1
[tex]2x+2(20)=80\\2x+40=80\\2x=80-40\\2x=40[/tex]
Dividing both sides by 2
[tex]\frac{2x}{2}=\frac{40}{2}\\x=20[/tex]
One roll of plain costs $20 and one roll of shiny costs $20 also.
Keywords: linear equation, elimination method
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