Question

Solve the simultaneous equations by substitution

x
+
2
y
=
20
x
=
6
+
5
y

Answer 1

Substitute x = 6 + 5y in x + 2y = 20:
6 + 5y + 2y = 20
7y = 20 - 6= 14
Y = 14/7 = 2
Now plug y = 2 into x = 6+5y
X = 6+ 5(2)
X = 16
Answer is x=16, y = 2

Answer 2

`x+2y=20; \ x=6+5y`

`6+5y+2y=20 \iff 7y = 20 - 6 \iff 7y = 14 \implies \bf y = 2`

`x = 6+5(2) = 6+10 \implies \bf x = 16`