HURRY!! A cement mason starts making concrete by mixing 2 1/2 pounds of sand to 3 1/4 pounds of gravel. The mason uses 414 pounds of sand and gravel to start the concrete. How many pounds of gravel does the mason use?

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

the formula of a slope:

we have the points (-2, 7) and (2, 3). substitute: