let

j = the miles the Julia ran

p = the miles that Pranav ran

Julia ran 30 miles more than Pranav

j = 30 + p

Julia ran 47 miles

j = 47

plug j = 47 into j = 30 + p

30 + p = 47

p = 47 - 30

p = 17 mi

Pranav ran 17 miles.