Let
x ----> orders served by Kala
y ----> orders served by Abdul
z ---> orders served by Joe
we have that
x+y+z=71 -----> equation A
x=y-5 -----> equation B
z=2y -----> equation C
solve the system
substitute equation B and equation C in equation A
so
(y-5)+y+(2y)=71
solve for y
4y-5=71
4y=71+5
4y=76
y=19
Find out the value of x
equation B
x=19-5=14
Find the value of z
equation C
z=2(19)=38
therefore
Lala served 14 orders
Abdul served 19 orders
Joe served 38 orders