An electric battery producer can use lithium (L) or a sodium compound (S) to make their batteries. The production function for batteries is:

q = 6L + 2S

1. Show a graph of two isoquants, one where q=120 and one where q=150, including intercepts (put S on the upper axis).
2. If the price of a unit of lithium is $400 and the price of a unit of sodium compound is $200, what material should the firm use for batteries to produce 120 units?
3. Are there increasing, constant, or decreasing returns to scale? Explain.