Below is an instruction that describes a task. Write a response that appropriately completes the request in Swahili. Please answer in Swahili.

### Instruction:
In the jar, there are 7 blue marbles, 11 red marbles, and some yellow marbles. If the chance of randomly picking a yellow marble is 1/4, how many yellow marbles are there?

### Response:
 Acha y iwe idadi ya mabulinge ya manjano.
Kuna jumla ya mabulinge 11 + 7 + y = 18 + y.
y/(18 + y) = 1/4.
4y = 18 + y.
3y = 18.
y = <<6=6>>6.
Kuna mabulinge 6 ya manjano.