Use equations (1) and (2) to find ( r ), the distance to the moon, in terms of ( rₑ ), and ( b ) in kilometers, given that ( rₑ = 7360 ) km, according to Eratosthenes c. 250 BC (which is an overestimate, ( rₑ ≈ 6400 ) km by modern measurements).
a. ( r = 7360b/b + 1840 )
b. ( r = 6400b/b + 1840 )
c. ( r = 7360b/b - 1840 )
d. ( r = 6400b/b - 1840 )