Step-by-step explanation: I started off by guessing a random number, i picked 10. So i multiplied 12x10 and i got 120. I added 120 with 120 until i got something close enough (720.) I got it right on the test as well- :)
so she has $550 and she did 20 cats and it costs $5 per cat and 5 x 20 is $100 and $550 - $100 = 450 and 450 divided by 10 ( because it's $10 per dog) is 45.