Sally and Marta had the same number of postcards. After Sally sold 18 of her postcards, Marta had 4 times as mow postcards as Sally. How many postcards did each girl have to begin with?

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Answer 1 · 2015-11-13T11:06:27

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Answer 2 · 2015-11-13T11:12:51

Each girl had 24 postcards.

Let the number of postcards with Sally and Marta be #x#.

After selling 18 postcards Sally had #x# - 18 postcards.

Then Marta will have 4 times of Sally.

4(#x-18#) = #x#

#4x# - #72# = #x#

Subtracting #x# on both sides

#4x# -#x# - #72# = #x# - #x#

#3x# - #72# = #0#

Adding 72 on both sides

#3x# -#72# + #72# = #0# + #72#

#3x# = #72#

Dividing both sides by 3

#3x/3# = #72/3#

#x# = 24

Hence each girl had 24 postcards in the beginning.