A toy store manager received a large order of Mr. Slinkums just in time for the holidays. The manager places $20\%$ of them on the shelves, leaving the other 120 Mr. Slinkums in storage. How many Mr. Slinkums were in this order?
I want to find out how many Mr. Slinkums were in the order, so I'll call that number x. The manager put $20\%$ of them on the shelves, so that means he put $0.2x$ on the shelves. The rest of them, 120, were left in storage. So I can write an equation: $0.2x + 120 = x$. To solve for x, I can subtract $0.2x$ from both sides, getting $120 = 0.8x$. Then, I can divide both sides by $0.8$, getting $x = 120/0.8 = 150$. Therefore, there were 150 Mr. Slinkums in the order.

