Can some explain me how to find the answers

(a) r = the weight of Rajesh's package and m = the weight of Mohib's package:

r = 2m + 3
r + m = 15

(b) The easiest way to solve this equation would be to use substitution.  The first equation says that r is equal to "2m + 3", so we can plug 2m + 3 in for the r in the second equation, and then solve for m:



Now that we have m, we can plug it into one of the equations to find r:



So, the weight of Rajesh's package is 11 pounds, and the weight of Mohib's package is 4 pounds.  This makes sense because both of these add up to 15 and Rajesh's package is three more than two times the weight of Mohib's package, as described in the question.

(c) Mohib's graph is the correct graph because it intersects at the correct point (4 on the Mohib axis and 11 on the Rajesh axis).  The other graph shows the intersection of the two lines at the wrong point, giving the wrong weights of the two packages.