Which is most likely to be the first step in solving a system of linear equations by substitution

Find the solution of this system of equation -7x+y=-20 9x-3y=36

1. find the area of the unshaded square 2. find the area of the large square 3. what is the area of the frame represented by the shaded region show

Ascientist has discovered an organism that produces five offspring exactly one hour after its own birth, and then goes on to live for one week without producing any additional offspring. each replicated organism also replicates at the same rate. at hour one, there is one organism. at hour two, there are five more organisms. how many total organisms are there at hour seven? 2,801 19,531 19,607 97.655