How do you solve the system 7r-2s=33 and 2r+7s=70?

1 Answer
Aug 22, 2015

Answer:

The solutions are
#color(blue)(s=8,r=7#

Explanation:

#7r-2s=33 #, multiplying by #2#
#color(blue)(14r)-4s=66 #.....equation #1#

# 2r+7s=70#, multiplying by #7#
#color(blue)( 14r)+49s=490#.....equation #2#

Solving by elimination
Subtracting equation #2# from #1#
#color(blue)(14r)-4s=66 #
#cancelcolor(blue)( -14r)-49s=-490#

#-53s=-424#
#color(blue)(s=8#

Finding #r# from equation #1#
#7r-2s=33 #
#7r=33+2s #
#7r=33+16 #
#7r=49 #
#color(blue)(r=7#