Answer:
Given the system of equation:
......[1]
......[2]
we can rewrite equation [2] as;
......[3]
Substitute equation [3] into [1] to eliminate x, and solve for y;
Using distributive property:
Combine like terms;
16 - 8y = -4
Add 4 to both sides we have;
20 - 8y = 0
Add 8y to both sides we have;
20 = 8y
Divide 8 to both sides we have;
Substitute the y-value in [3] we have;
x = 8 - 5 = 3
Therefore, the expression should be substituted into the first equation is, and also the value of x = 3 and y = 2.5