225 serves because you need to set up a proportion. The proportion is 2/5=90/x then solve for x by cross multiplying, which gives you 450=2x. Then divide 450 by 2 which gives you 225. Work shown in the attached picture.
Reading this out loud?
nine plus seven x
$61 x 3= $183
$183 x .08225= 15.11
$183 + 15.11= $198.11