Solve the following equation mentally. 𝑓 divided by two equals five.
To solve this equation mentally, we need to think about what is happening. We know that something divided by two equals five. We also know that dividing by two is like cutting something in half. If we have a whole brick, our whole something is 𝑓. But one-half of that 𝑓 equals five. And if half of the 𝑓 equals five, the other half also has to equal five, which means the whole brick is 10. 𝑓 must be equal to 10. We can do a mental check. Is 10 divided by two equal to five? We know this is true because five times two equals 10. And so, we say that 𝑓 equals 10.