Answer:
7 times during the first 15 minutes
Step-by-step explanation:
Remember that
so
Decompose the numbers 18 and 42 in prime factors
we know that
Find the least common multiple (LCM)
The LCM is
we need to find all multiples of 126 that are less than or equal 900.
therefore
7 times during the first 15 minutes
Steps of adding 7+(-10) using number line are as following:
1) Draw a number line by ranging from -10 to +10.
2) Point out 7 on the number line.
3) Because -10 is added to 7 on the number line, please move 10 numbers left to 7 on the number line. We always go left in addition of a negative number on the number line.
4) The number we reach -3 on left side would be our final sum.
5) From the number we can clearly see that moving 10 number on left to 7, we get -3.
Note: We are moving left because of negative sign in front of 10.
