Consumer math:using credit question #1- Sal took out a 21-day payday loan from the just loans store. He borrowed $350 and is being charged $75 in interest. What is the APR for this loan?
A-21.4%
B-75.86%
C-278.65%
D-371.95
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i just took the test, the correct answer is .. 31.5 in.

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