Question:
Mr Wong bought a number of red, blue and green balloons. The ratio of the number of red balloons to the number of blue balloons was 5 : 4 while the ratio of the number of blue balloons to the number of green balloons was 3 : 7. After bursting some green balloons and buying another 168 blue balloons, he found that there was a decrease of 25% in the total number of blue and green balloon. In the end, the number of red, blue and green balloons he had was 1440.
(a) How many balloons did Mr Wong have at first?
(b) How many green balloons were burst?