Respuesta :

we have that
2u+v=4

part a) 
express variable v in terms of u 
2u+v=4-------> v=4-2u

the answer part a) is
v=4-2u

Part b) express variable u in terms of v 
2u+v=4-------> 2u=4-v-------> u=(4-v)/2

the answer part b) is
u=(4-v)/2