SOLUTION: I am working with these word Problem and what I believe the way to solve it but I don't end up with a whole number answer. What am I doing wrong? Loretta owns a pet shop that sp

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Question 657386: I am working with these word Problem and what I believe the way to solve it but I don't end up with a whole number answer. What am I doing wrong?
Loretta owns a pet shop that specializes in exotic tropical fish. In April,Loretta doubled the number of fish she had on hand,and then sold 30 of them. In May,she tripled the number of fish she had on hand, and then sold 54 of them. In June, she quadrupled the number of fish she had, and then sold 72 of them. she now had 48 fish left. How many fish did she start with?
x=fish she started with
(2x-30)+(3x-54)+(4x-72)=48
Thank You for your help!

Found 2 solutions by josmiceli, kevwill:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
She starts with x
Then 2x
Next +2x+-+30+
Then +3%2A%28+2x+-+30+%29+-+54+
Then +4%2A%28+3%2A%28+2x+-+30+%29+-+54+%29+-72+=+48+
+12%2A%282x+-+30%29+-+216+-+72+=+48+
+24x+-+360+-+216+-+72+=+48+
+24x+=+360+%2B+216+%2B+72+%2B+48+
+24x+=+696+
+x+=+29+
She started with 29 fish
check:
+29+
then +58+
then +58+-+30+=+28+
then +3%2A28+-+54+=+30+
then +4%2A30+-+72+=+48+
+120+-+72+=+48+
+48+=+48+
OK

Answer by kevwill(135) About Me  (Show Source):
You can put this solution on YOUR website!
The problem with our equation is that it uses only one variable (x) to represent the number of fish Loretta started with each month. You can't assume it's the same number each month, so you can't use a single variable.
Let's take it one month at a time, working backward from June.
After selling 72 fish in June, she had 48 left, so she started June with 48+72 = 120 fish.
Since she quadrupled the number of fish in June, she must have finished May with 120/4 = 30 fish. This is after selling 54 fish, so she started May with 30+54 = 84 fish.
Since she tripled the number of fish in May, she must have finished April with 84/3 = 28 fish. This is after selling 30 fish, so she started April with 28+30 = 58 fish.
Since she doubled the number of fish in April, she must have started with 58/2 = 29 fish.