Problem solving

 Today we used place value to solve an equation. 

First we started with the ones by adding them togather 4 + 6 + 7=10. Then we add them togather 10+7=17.

Next we added the tens togather wich is 20 + 20 + 10=50. Next we added the tens and ones togather which is 50+17=67.

Now we know she practised for 67 minutes. So then we subtracted 67 from 90. 0-7 is not possible so we did 10-7=3. 

Lastly we did 80-60=20 then we added that togather which is 23 so Leilani needs to practise for another 23 mins.

I didn't know what to do so I waited to see what other people examples are so I could think of one.