Abag contains both black and red marbles. the ratio of black to red marbles is 3: 4.

a: what is the ratio of black marbles to the total number of marbles in the bag?
b: what is the ratio of red marbles to the total number of marbles in the bag?

select two answer choices. select one answer choice for question a, and select one answer choice for question b.

b: 4: 1
b: 3: 1
b: 3: 7
a: 4: 7
a: 3: 7
a: 4: 1
b: 4: 7
a: 3: 1
a: 4: 3
b: 4: 3