In science notation, 670,000,000+700,000,000=? how to you show your work

a) 670,000,000 + 700,000,000 = 1,370,000,000
b) Divide 1,370,000,000 by 9 (9 because that is how many digits behind the first comma).
c) You should get 1.37
d) Now, multiply 1.37 by 10^9. You should not actually multiply these numbers; just write your problem.
e) It should look like this: 1.37 x 10^9

The third and fourth box.

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.