easy
just remember
you can do ANYTHING to an equaiton as long as you do it to both sides
try to get place holder by itself
4.5b+9=90
minus 90 from both sides
4.5b+9-9=90-9
4.5b+0=81
4.5b=81
either divide both sides by 4.5 or double 4.5 to get rid of the decimal
I will double
double both sides
9b=162
divid both sides by 9
b=18