How do you solve #7m+n=41# and #m-9n=45# using substitution?

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Answer 1 · 2016-05-16T20:22:45

#n=-137/32#
#m=1449/224#

#7m+n=41#

#color(green)(7m)=41-n" (1)"#

#m-9n=45" let's extend both side of equation by 7"#

#color(red)(7)*m-color(red)(7)*9n=color(red)(7)*45#

#color(green)(7m)-63n=315#

#41-n-63n=315#

#41-64n=315#

#-64n=315-41#

#-64n=274#

#n=-274/64=-137/32#

#"use (1)"#

#7m=41+137/32#

#7m=(1312+137)/32#

#7m=1449/32#

#m=(1449)/(32*7)#

#m=1449/224#