No machine gives you energy. Every one of them trades: less force, more distance, and the product stays put. That trade has a name — mechanical advantage.

For a lever, $MA = \dfrac{d_e}{d_l}$ — M A equals d-e over d-l. The subscripts are the whole convention, so fix them now: $d_e$ is the effort arm, pivot to your hands, and $d_l$ is the load arm, pivot to the load, both in metres. $MA$ is a bare ratio — metres over metres, no units — and it says how many times the bar multiplies your pull. An MA of 4 means the effort is a quarter of the load. A lever is just a moment balance wearing work clothes.

A block and tackle does the same trick with rope: $F = \dfrac{W}{n}$, where $W$ is the load in newtons, $n$ is the number of rope sections actually supporting the moving block (a plain count, no units), and $F$ is the effort in newtons. Six sections, a sixth of the load — and six metres of rope hauled for every metre the load rises. The energy bill is never discounted.

Then reality takes its cut. $\eta = \dfrac{W_{out}}{W_{in}}$ — eta equals W-out over W-in, with $\eta$ the Greek letter eta. $W_{out}$ is the useful work delivered and $W_{in}$ the work you paid in, both in joules; the ratio is bare, and quoting it as a percentage is a courtesy, not a unit. The shortfall went to friction, heat and noise. An efficiency above 100% is not a good machine — it is an arithmetic error.