Question

ayudaaa porfavor es muy urgente es por el metodo de sustitucion

Answer 1

7x - 8y = -2----------------------------------- 1
9x -  y  = 81 ---------------------------------  2
 despejando 1
7x -8y = -2
  x = (-2+8y)/7----------------------------  3
reemplazando 3en 2
9(-2+8y)/7 -y = 81
-18+72y -7y = 567
65y = 567+18
65y = 585
y = 585/65
y = 9
hallando x   x = (-2+8y)/7
x = (-2+8*9)/7
x = (-2+72)/7
x = 70/7
x = 10