B. MRS + mST = MRT Q R. S

MRS is the demand side of equation while MRT is for the supply side.

MRS defines how much a consumer is willing to give up of good X for 1 additional unit of good Y to stay on the same utility level. It is shown by indifference curve. MRS = Price of X/ Price of Y

Similarly, MRT is how much a supplier is willing to give up producing good X for 1 additional unit of good Y. It is shown by Production Possibility Frontier. MRT = MC of X/ MC of Y

10 - 75

step-by-step explanation:

there's nothing attached so it's most likely anything in that range.

there is only one way to arrange all the eight relative to each other because they are not distinct. we have

now there are nine places to place an (and not more than one in one place).   because we have four symbols, we need to choose four of these nine places to insert an . order does not matter because the are not distinct.

thus there are 1 · c(9,4) ways, or, if we calculate it,

thus there are 126 ways to form such "words."