How to write 2,000,000,000 in standard form

Solve 3x-18=2y and 5x-6y=6 by elimination show work

Axel follows these steps to divide 40 by 9: start with 40. 1. divide by 9 and write down the remainder. 2. write a zero after the remainder. 3. repeat steps 1 and 2 until you have a remainder of zero. examine his work, and then complete the statements below.

Which expression gives the exact value of x?