Pat's age today, plus Pat's age 5 years ago, equals 21. What is Pat's age today?

2 Answers
May 8, 2018

13 years old

Explanation:

Pat's age today is a variable since we don't know its value. Let's say that's #x#.
Pat's age 5 years ago would be #x-5#.

Add those together and you have 21, so...
#x# added to #x-5# is #21.#

Mathematical form: #x+(x-5)=21#
Let's simplify!

#x+x-5=21#
#2x-5=21#
#2x=26#
#x=13#


Checking your work:
#(13)+(13)-5\stackrel(?)(=)21#
#26-5\stackrel(?)(=)21#
#21=21\sqrt#

May 8, 2018

Pat is 13 years old

Explanation:

Let's write the sentence in mathematical terms, using #P# as "Pat's Age"

#P+(P-5)=21#

#P+P-5=21#

#2P-5=21#

#2Pcancel(-5)color(red)(cancel(+5))=21color(red)(+5)#

#2P=26#

#(cancel(2)P)/color(red)(cancel(2))=26/color(red)(2)#

#color(green)(P=13)#