4a + 63 = 83 ?
Find a solution for a ?​

Using complete sentences, describe the central economic problem facing all humans. why does this require people to make choices? how can this result in opportunity costs?

Ahis which describe the horizons in a soil profile? check all that apply. horizon a is mineral deficient. bedrock lies below the soil layers. te horizon o forms from organic material, horizon b undergoes the least amount of change. horizon c is least affected by the soil formation process.

Largest layer of atmosphere international space station orbits ultraviolet radiation causes ionization the phrases describe what layer of earth's atmosphere?