The ratio of red marbles to blue marbles is 4 to 5. If you had 81 marbles total, how many would be blue?

Question

IM CONFUSION!!!! please help meh. #MATHRULES

Answer 1

A 4 to 5 ratio can be written like 4:5

Add the 4 and 5 to get 9

So 4/9 are red and 5/9 are blue

Multiply 5/9 x 81 to get the number of blue which is 45