How do you solve the system of equations #\frac { 18} { n } = \frac { 54} { n + 40}#?

2 Answers
Jun 3, 2018

#n=20#

Explanation:

By cross multiplication we get
#18(n+40)=54n#
Note that #3*18=54#
so
#n+40=3n#

#2n=40#
so #n=20#

#n = 20#.

Explanation:

We have,

#color(white)(xxx) 18/n = 54/(n + 40)#

#rArr 1/n = 3/(n + 40)# [Divide both sides by #18#]

#rArr 3n = n + 40# [Cross-multiply]

#rArr 3n - n = canceln + 40 cancel(-n)# [Subtract #n# from both sides]

#rArr 2n = 40#

#rArr n = 20# [Divide both sides by #2#].

And We got our answer. Hope this helps.