# Problem №1 (10 points)

The distance between Ivan's house and his grandmother's house is 12 km. At exactly $12 \stackrel{00}{}$ Ivan left his house and started walking straight to his grandmother's house at a speed of 1 m/s. At $12^{\frac{30}{}}$ Ivan's parents called his grandmother, told her that Ivan was on his way, and the grandmother let the dog Tuzik run to meet him. Tuzik runs at a speed of 9 m/s. Determine the time when Tuzik will reach Ivan.
# Solution:

In half an hour, Ivan will walk:

$S=vt=1 \cdot 30 \cdot 60=1800$ meters.

That is, between him and Tuzik remains:

$12000-1800=10200$ meters, which Ivan and Tuzik will overcome in:

$t=\frac{10200}{1+9}=1020 s=17$ min.

That is, the moment when Tuzik reaches Ivan is $12^{47}$

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