Answer:
a. it has no solution
b. you can only substitute by making either the 'x' or 'y' the subject of either of the two equations.
Step-by-step explanation:
3x - 9y = -13.............. eqn 1
x - 3y = -7................... eqn 2
from eqn 2
x - 3y = -7, substitute by making 'x' the subject
x = -7 + 3y.................. eqn 3
put eqn 3 into eqn 1
3x - 9y = -13
3( -7 + 3y) - 9y = -13
-21 + 9y - 9y = -13
9y - 9y = -13 + 21
0 = 8, which is not possible.
