Answer :
[tex]x+y=500[/tex]
[tex]0.05x+0.085y=40 [/tex]
Multiply both sides of second equation by 20 to get[tex]x+1.7y=800[/tex]
Subtract that from first equation to get [tex]0.7y=300[/tex]
Divide both sides by 0.7 to get [tex]y=428.571[/tex], so about $428.57 was spent in store. This leaves [tex]500-428.57=$71.43[/tex] that was spent online
[tex]0.05x+0.085y=40 [/tex]
Multiply both sides of second equation by 20 to get[tex]x+1.7y=800[/tex]
Subtract that from first equation to get [tex]0.7y=300[/tex]
Divide both sides by 0.7 to get [tex]y=428.571[/tex], so about $428.57 was spent in store. This leaves [tex]500-428.57=$71.43[/tex] that was spent online