Average 81602

A monthly fee of 60 crowns is paid for the phone and 3 crowns for each call. How many calls did we have when one call cost us an average of 4 crowns and 20 pennies?

Correct answer:

n =  50

Step-by-step explanation:

$$\begin{gathered} h=4.20\text{SK} \\ h\cdot n=60+3\cdot n \\ 4.2\cdot n=60+3\cdot n \\ 1.2n=60 \\ n=\frac{60}{1.2}=50 \\ n=50 \end{gathered}$$

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