a20−ba=30 and b=1Substitute the values into the expression and simplify.a20−b=3020−1Every whole number is being divided by 1 which is not written.1=11a20−b=3020−113020−11=301×20−1×303020−11=3020−303020−11=30−10=−31Note: 10 divides itself once and 30,3 times or the zeros cancel each other.