Level 2 PSLE A box contained black balls and green balls. 40% of the balls were green. After some red balls were added to the box, 28% of the balls were green. What percentage of the balls in the box were red?
Level 2
A bag contains blue and green marbles in the ratio of 2 : 5. There is a total of 91 marbles in the bag. How many more blue marbles must be added into the bag so that the number of blue marbles will be the same as the number of green marbles?