63 is 90% of what number using number lines

Well, the answer is 70 but, I don't know how to find it using a number line. Hope I could help!

First of all make a number line by dividing the line into 10 equal sections. You could make a line 10cm long divided into 1cm divisions or boxes. Now mark off the 9cm position. That’s 90%. Next write the number 63 over all 9 sections. Each section represents 63/9=7. So the last section must also be 7. When we add 7 to 63 we get 70. So since the 10cm line represents 100%, 70 must be 100%. That is the answer using a number line.