Final answer:
Before trade, Econland and Rivermoor were collectively producing 155 skateboards, obtained by adding Econland's production of 75 skateboards to Rivermoor's production of 80 skateboards.
Step-by-step explanation:
The question is asking for the total production of skateboards between two countries, Econland and Rivermoor, before trade occurs. To calculate this, we simply add the production of skateboards from both countries. Econland is currently producing 75 skateboards, and Rivermoor is producing 80 skateboards. Collectively, before trade, Econland and Rivermoor were producing 155 skateboards.
Before trade, the total number of skateboards being produced collectively between Econland and Rivermoor is calculated by adding their individual productions. Econland produces 75 skateboards, and Rivermoor produces 80 skateboards.
Total skateboards = Econland's skateboards + Rivermoor's skateboards
= 75 + 80
= 155
Therefore, before trade, the two countries together were producing a total of 155 skateboards. This calculation involves summing up the individual quantities produced by each country in the given scenario.