# math

posted by
**sandy**
.

2/3 over 10 equals 1.8/r solve for r.

(2/3)/10 = 1.8r.

First, invert and multiply the denominator; i.e.,10.

(2/3)*(1/10) = 1.8/r

2/30 = 1.8/r

Now cross multiply.

2r = 30*1.8

2r = 54

Now divide both sides by 2

2r/2 = 54/2

r = 27

check my thinking. check my work.