The second property: A:B=C:D, if n >；; 0, then there is nA:nB=nC:nD.

1 " a:b = 1/2: 1/3 & gt； & gt& gt 1/2 * b = 1/3 * a & gt； & gt& gt2a=3b, that is, a: b = 3: 2 and a = 3/2b.

B:c=0.3:0.2=3:2, that is, c=2/3b, so

a:b:c = 3/2b:b:2/3b = 3/2: 1:2/3

Multiply it by 6:a:b:c = 9:6:4.

2 "Assuming that the latter term plus X can keep the ratio unchanged, you can get 2.5: 5.25 = (2.5+1.5): (5.25+x).

According to property one, we can get 5.25*4=2.5*(5.25+X).

The result of Jie's solution is x = 5.25 *1.5/2.5 = 3.15.

3:X:36=2:9 >& gt& gt& gtx=36*2/9=8