Nick is three years young than Sam. The sum of their ages is 33. How old are they?

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Answer 1 · 2018-04-14T05:00:04

Sam: 18
NIck: 15

Let Nick's age be x and let Sam's age be y.
Translate the sentence into 2 equations to get a system of equations:
#x=y-3#
#x+y=33#

There are several ways to solve a system of linear equations. "Substitution" is one of those methods:

Since #x=y-3# is solve for x, we will replace the #x# in the second equation with #y-3#.

#x+y=33#

#(y-3)+y=33 " "# Now, solve for y

#2y-3=33#

#2y=36#

#y=18 " "# Once we have y, we can substitute y back into one of the original equations to find x.

#x=y-3#

#x=(18)-3#

#x=15#