Find the perimeter of the triangle

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.

Asequence is defined recursively using the formula f(n + 1) =f(n) - 5. which sequence could be

Iwas absent when my class learned this and my teacher is to lazy to teach it to me explain this to me .