Answer
a)Steve plans to run $11$ miles in week $4$.
b) Steve will run $20$ miles in week $10$.
Work Step by Step
a) When $w = 4$
$R = 1.5w+5$
$R = 1.5(4) + 5$
$= 6+5$
$= 11$
Steve plans to run $11$ miles in week $4$.
b) When $R = 20$
$R = 1.5w+5$
$20 = 1.5w+5$
$20-5 = 1.5w$
$15 = 1.5w$
$w = 10$
Steve will run $20$ miles in week $10$.
