Grades 9-10 Video Solutions 2021-video 2021 9-10/10

Video Transcription

Problem number 10 states, The little kangaroo chose a special number. She gets the same result when she subtracts one-tenth from her number as she does when  she multiplies it by one-tenth. What is her number? So we know that this kangaroo picked some special number which we will represent as  A. The problem tells us that if we subtract one-tenth from it, it will result in the same number as if we multiplied it by one-tenth.  So mathematically, one-tenth A equals A minus one-tenth. So now let's solve for A. Let's do this by multiplying both sides by 10. So we get A equals 10A minus 1.  Subtract 10A from both sides, we get minus 9A equals minus 1. Now we seem to divide both sides by minus 9. The negatives cancel out and we get A equals one-ninth.  So the kangaroo's special number was one-ninth. So the question asked us, what is her number? The answer is one-ninth, letter E.

Video Summary

Problem number 10 states, The little kangaroo chose a special number. She gets the same result when she subtracts one-tenth from her number as she does when she multiplies it by one-tenth. What is her number? So we know that this kangaroo picked some special number which we will represent as A. The problem tells us that if we subtract one-tenth from it, it will result in the same number as if we multiplied it by one-tenth. So mathematically, one-tenth A equals A minus one-tenth. So now let's solve for A. Let's do this by multiplying both sides by 10. So we get A equals 10A minus 1. Subtract 10A from both sides, we get minus 9A equals minus 1. Now we seem to divide both sides by minus 9. The negatives cancel out and we get A equals one-ninth. So the kangaroo's special number was one-ninth. So the question asked us, what is her number? The answer is one-ninth, letter E.

Keywords

kangaroo

special number

one-tenth

solve

one-ninth