(12y)+12 y=15 do i multiply 12 and 15 then add 12

50 yellow marbles.

Step-by-step explanation:

Information:

170 marbles

RED : BLUE : YELLOW

9 : 3 : 5

Solving:

To find out how many yellow parts there are, we need to find out how many marbles 5 parts account to.

Altogether, 9 + 3 + 5 = 17. This means there are 17 parts.

The bag contains 170 marbles and the ratio adds up to 17 parts.

We can figure out what 1 part of the ratio accounts to by dividing 170 by 17.

= 10.

1 part = 10

Now remember yellow is 5 parts, now that we know that 1 part is 10, we need to multiply 10 by 5 to find out how many yellow marbles we have.

5 x 10 = 50.

Therefore we have 50 yellow marbles.