ANSWER PLEASE If we change one side of a square by factor of 5, of 0.5, of 12 and of 1/12 , by what factor will the perimeter change?

because linear equations are a lot simpler than quadratics equations, and linear equations formula is a lot easier to memorize. that's why i think they're harder.

just get this app called photo math it should be able to do those

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source:  

we would need a picture of the quadrilateral in order to answer the question. also, it seems that the question is missing some components.