The best way to approach these problems is to set up a simple equation.

Note that the word "of" means multiply in math, and "is" means equals. Also. "what number" is an unknown quantity...a variable.

So, 0.45 times "x" = 50 or 0.45x=50 divide both sides by 0.45, so x=50/0.45=111.11

Remember that a percent needs to be changed into a decimal-->divide the percent by 100, so 45% = 0.45