Can someone help plz?!

10 cm

Step-by-step explanation:

The diameter is a chord (line) that connects on both ends of a circle which includes the center point of the circle. The radius comes from the center point of the circle to one end of the circle.

Diameter is therefore 2 radii (radius).

So if diameter is given and you want to find the radius, divide it by two to find the answer.

20 ÷ 2 = 10 cm

answer set (b) 0.5, 3/4 80% is in order from least to greatest.  

step-by-step explanation:

in order to compare rational numbers to each other, it is much easier if they are in the same form.   typically, the best form in which to evaluate rational numbers is in decimals.   in order to convert a percent to a decimal, you would divide the given percentage by 100.   you can also accomplish the conversion by moving the decimal point over two places to the left.   for example, the decimal value of 80% is 80/100, or 0.8.   in order to convert a fraction to a decimal, you need to divide the numerator by the denominator.   for example, 3/4 is 0.75.   so, for choice (b) 0.5 3/4 (0.75), 80% (0.8) is the only choice in which the numbers are in order from least to greatest.  

9 x 8 divided by (5-3)=36