> > there are nine books stacked on a shelf the thickness of each book is 1 inch or 2 inches the height of the stack of nine books is 14 inches which systems of equations can be used to determine X the number of 1 inch thick books in the stack And y the numbe

# there are nine books stacked on a shelf the thickness of each book is 1 inch or 2 inches the height of the stack of nine books is 14 inches which systems of equations can be used to determine X the number of 1 inch thick books in the stack And y the numbe

## there are nine books stacked on a shelf the thickness of each book ...

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### there are nine books stacked on a shelf the thickness of each book is 1 inch or 2 inches the height of the stack of nine books is 14 inches which systems of equations can be used to determine X the number of 1 inch thick books in the stack And y the numbe

there are nine books stacked on a shelf the thickness of each book is 1 inch or 2 inches the height of the stack of nine books is 14 inches which systems of equations can be used to determine X the number of 1 inch thick books in the stack And y the number of 2 inch thick books

1x + 2y = 14 and x + y = 9 You isolate the x in the x + y = 9 equation to x = 9 - y and plug it into the first equation.
That gives you 1(y-9) + 2y = 9.
Simplify and solve for 1y - 9 + 2y = 9 +9 +9 1y + 2y = 18, so 3y = 18.
Diving each side by 3 and y = 6.
Plug y = 6 into the second original equation and you get x + 6 = 9, so x = 3.