Lucy bought a doormat for $7 and some placemats for $2 each. her total average cost per item was $3. create a rational equation, and determine how many placemats she bought.

Lucy bought 4 placemats.

Step-by-step explanation:

Let n be the number of placemats Lucy bought.

1 doormat = $7

1 placemat = $2

n placemats = $2n

Total = $(7+2n)

Total number of objects bought = n+1

Average

So,

Solve this equation:

Hence, Lucy bought 4 placemats.

i really dont know

step-by-step explanation:

solution:

→c= a b , that is product of a and b is possible only when when a is m × n matrix and b is n × p matrix.

that is, number of columns of a= number of rows of b.

so, size of matrix , c= a b is , if a = (m × n)matrix

b= (n × p)matrix

then a b = [ (m × n)matrix] ×[   (n × p)matrix ]

→→c= a b= [m × p ] matrix

→→size of product a b will be equal to = number of rows of a × number of columns of b