Crayon basket calculation

Wendell has 4/5 the number of colored pencils. But if Mary took 1/2 of it, there would be 20 crayons left.

How many crayons were still in the pencil case before Wendell's collection?

Final Answer:

p =  50

Step-by-step explanation:

$$\begin{gathered} v=4/5p \\ v-v/2=20 \\ v=40 \\ p=\frac{5}{4}\cdot v=\frac{5}{4}\cdot 40=\frac{5\cdot 40}{4}=\frac{200}{4}=50 \end{gathered}$$

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