Help me out man i’ll give a crown to the smart one

An appliance store sells a washer-dryer combination for $1800. if the washer costs $300 more than the dryer, find the cost for each appliance.

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

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