Tell whether the ratios form a proportion. 9:3 and 45:15
.yes

.no
Explain. How do you know?

Yes
9:3- 3:1
45:15 - 3:1

Order of operations tell us that we do multiplication and division first in the order we get to them, and then addition and subtraction after.  24/4*3-6/3+8.  We'll divide 24 by 4 to get 6, but then we immediately have to multiply 6 times 3 to get 18.  Then move down to 6 divided by 3 to get 2.  So what we have now is 18 - 2 + 8 which is 24.