sally and marta had the same number of postards. after sally sold 18 postards, marta had 4 times as many as sally. how many ostcards did eeach girl have to begin with
Sally has X postcards.
Marta has X postcards.
X = 4(X-18)
Solve for X.
24
To solve this problem, we can set up an equation based on the information given. Let's denote the initial number of postcards Sally and Marta had as "x".
After Sally sold 18 postcards, she had "x - 18" postcards left.
According to the problem, Marta had 4 times as many postcards as Sally after the sale. So we can write the equation:
4(x - 18) = x
Now we can solve this equation to find the value of x, which represents the initial number of postcards both girls had.
4x - 72 = x
Subtracting x from both sides:
4x - x = 72
3x = 72
Dividing both sides by 3:
x = 72 / 3
x = 24
Therefore, both Sally and Marta had 24 postcards to begin with.