Add 21 to both sides, so you get 9z = 81
three hundred thousand twenty-one two hundred nine
Step-by-step explanation:
50 tens is equal to 500 because if you multiply a number by 10, you just add a 0 behind it.
4 hundreds is literally just 400.
So 500 x 400 = 200,000
40 * 10 = 400
5 * 100 = 500
400 x 500 = 200,000
so both sides are equal to 200,000 and therefore the equation is true.
