Question

120=rt
120=2r(t-30)
Solve for R

Answer 1

use substitution method

Answer 2

r=120/t from first equation solving for r

120=2(120/t )(t-30) plug in r into second equation
120=2(120/t )(t-30) now solve for t

t= 60 plug that back into the top equation

120=60*r
120/60=r
r= 2

ALSO i think it would have been faster if you solve for t first then plug in to equation 2 then solve for r and ended there :D