Answer :
if N = 8
if M = 7
then the equation is 8(2) - 7
do the multiplication first 8(2) = 16
now do the subtraction 16 - 7 = 9
if M = 7
then the equation is 8(2) - 7
do the multiplication first 8(2) = 16
now do the subtraction 16 - 7 = 9