How do you solve 21x-15y=24 and 6x+10y=24?

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Answer 1 · 2018-04-03T12:28:33

#x=2#
#y=6/5#

#21x-15y=24# ---(1)
#6x+10y=24# --- (2)

From (2),

#6x=24-10y#
#x=4-5/3y# --- (3)

Sub (3) into (1).

#21(4-5/3y)-15y=24#
#84-35y-15y=24#
#60=50y#
#y=6/5# --- (4)

Sub (4) into (3)
#x=4-5/3times6/5#
#x=2#

Answer 2 · 2018-04-03T12:39:24

#x=2# and #y=6/5#

As both equation equal 24, equate them:

#21x-15y=6x+10y#

#15x-15y=10y#

#15x=25y#

#3x=5y#

Substitute this into #6x+10y=24#

#6x=2##xx##3y#

#=># #(2##xx#5y)+10y=24

#=># #10y+10y=24#
#=># #20y=24#
#=># #y=6/5#
Substitute #y=6/5# into either equation to find #x#

#6x+10##xx##6/5=24#
#6x+12=24#
#x=2#