Question

Solve the simultaneous equations by substitution

3
x
+
y
=
24
y
=
x
+
4

Answer 1

the solution is (5, 9)

Explanation:

Please draw your table across the page, not up and down:

3x + y = 24 and y = x + 4

Substitute the 2nd equation into the first, to eliminate y:

3x + x + 4 = 24, or

4x = 20. Then x must be 5. From the second equation, using substitution, we obtain y = 5 + 4 = 9, and so the solution is (5, 9).