Which of the following are true?

fractions and ratios cannot have zero in the denominator.
fractions and ratios are different names for the same thing.
some fractions and ratios can be written as mixed numbers.
fractions and ratios can be simplified the same way

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?

Find the measure of angle c in the following triangle.

Aliter of water contains about 3.35 x 10^25 molecules. a certain river discharges about 2.9x 10^8 l of water every second. about how many molecules does the river discharge every minute? write your answer in scientific notation