Question

please answer grade 7 20 points
4. Ahmed thought of a number, he doubles it, added 4 in it, his answer is 34. what is the number

Answer 1

Answer:

It can be shown really easily. If you want to calculate it, just write it out:

2n+62−n=?

Write it as following:

2n+62−2n2=?

Combine fractions:

2n+6−2n2=?

And voila:

62=3

In other words, if you first double the number, add something and divide by two, the contribution of your number is now just that number again plus 6 divided by two. If you then subtract your number, you simply get 6 divided by two.