Solving a word problem with three unknowns using a linear equation

Question

Heather, Kareem, and Reuben served a total of
131
orders Monday at the school cafeteria. Reuben served
4
times as many orders as Kareem. Heather served
7
fewer orders than Kareem. How many orders did they each serve?

 

Answer 1

h + k + r = 131

r = 4*k

h = k -7

 

(k-7) + k + (4k) = 131

6k-7=131

6k=138

k=23

 

r = 23 * 4 = 92

 

h = 23-7 = 16