Laura will go for a run during her lunch break if the temperature is between 6 0 ∘ F 60 ∘ F60, degrees, start text, F, end text and 8 0 ∘ F 80 ∘ F80, degrees, start text, F, end text. The average speed, S SS, in miles per hour, at which Laura runs is dependent on the temperature, t tt, in degrees Fahrenheit ( ∘ F ) ( ∘ F)left parenthesis, degrees, start text, F, end text, right parenthesis, at the start of her run and can be modeled by the function S ( t ) = 6 + 0.1 ( 80 − t ) S(t)=6+0.1(80−t)S, left parenthesis, t, right parenthesis, equals, 6, plus, 0, point, 1, left parenthesis, 80, minus, t, right parenthesis. The distance, D DD, in miles, that she can run in 30 3030 minutes given that her average speed is x xx miles per hour can be modeled by the function D ( x ) = 0.5 x D(x)=0.5xD, left parenthesis, x, right parenthesis, equals, 0, point, 5, x.