Question

How many tens should be added in the result after subtracting 10 units from 42 tens for getting sum 500

Answer 1

420 - 10 =410
410 + 9 tens = 500

Answer 2

9 tens should be added to the result after subtracting 10 units from 42 tens for getting the sum five hundred.

=>x*10+42*10-10=500
=>10x+420-10=500
=>10x+410=500
=>10x=90
=>x=9