Robert and Caleb each had a collection of rocks. Caleb had 2/9 as many rocks as Robert. When Robert lost 40 rocks, Caleb then had twice as many as Robert. How many rocks were in Robert's collection at first?

C = 2/9R

C = 2(R-40)

2/9R = 2(R-40)

Take it from there. :))

=^._.^=

Is the answer 45?

2/9R = 2R - 80

80 = 16/9R

R = 45

yayyy :))