Maths problem[ Percentages]

1)A is 50% greater than B , so A = 1.5B
A+B = 1.5B + B = 2.5B
A-B = 1.5B - B = 0.5B
percentage of A+B is A-B = (A-B)/(A+B) * 100%
= 0.5B / 2.5B * 100%= 0.5/2.5 * 100%= 20%
2)x is 60% more than y , so x = 1.6y
percentage is y less than x = (x-y)/y * 100%
= (1.6y - y)/1.6y * 100%
= 0.6 / 1.6 * 100%
= 37.5%
3) A is 70% of B , so A = 0.7B
C is 30% greater than A , so C = 1.3A = 1.3(0.7B) = 0.91B
C = 0.91B
C/B = 0.91
percentage of B is C = C/B * 100% = 0.91 * 100% = 91%


2009-07-09 19:56:06 補充：
For Q2 ,it should be percentage is y less than x = (x-y)/x * 100%

thx so much!