Question

u+v=10 2u-3v=5 igualacion

Answer 1

Despeja la misma incognita en ambas ecuaciones:
u = 10 - v
u = (5 + 3v)/2

Iguala ambos resultados:
10 -v = (5+3v)/2

Opera
20 - 2v = 5 + 3v
20 - 5 = 3v + 2v
15 = 5v
v = 15: 5 = 3
u = 10 - 3 = 7