Find the value of x on this proportion

solving proportions is simply a matter of stating the ratios as fractions, setting the two fractions equal to each other, cross-multiplying, and solving the resulting equation. You'll probably start out by just solving proportions, like this:

Find the unknown value in the proportion:  2 : x = 3 : 9.2 : x = 3 : 9First, I convert the colon-based odds-notation ratios to fractional form:.Then I solve the proportion: 
9(2) = x(3) 
18 = 3x 
6 = xFind the unknown value in the proportion:  (2x + 1) : 2 = (x + 2) : 5(2x + 1) : 2 = (x + 2) : 5 ADVERTISEMENT First, I convert the colon-based odds-notation ratios to fractional form:Then I solve the proportion: 
5(2x + 1)  =  2(x + 2) 
10x + 5  =  2x + 4 
8x  =  –1 
x = –1/8