Answer:
No. of yellow balloons = r - b -
Explanation:
Total number of balloons = r
No of blue balloons = b
Blue balloons are twice the no of green balloons. so
No. of green balloons =
No of yellow balloons = ( Total number of balloons ) - ( No of blue balloons ) - ( No. of green balloons )
⇒ No. of yellow balloons = r - b -