Solve the system of equations by substitution x+y=18, y=5x

One way to do it is

Plug in y so 5y + x = 18

Divide both sides by 5 to get y alone

Subtract the answer of 18:5 = 3.6

3.6 - 18 = 14.4

14.4 is your answer

(3, 15)

Step-by-step explanation:

Given the 2 equations

x + y = 18 → (1)

y = 5x → (2)

Substitute y = 5x into (1)

x + 5x = 18

6x = 18 (divide both sides by 6)

x = 3

Substitute x = 3 into (2) for corresponding value of y

y = 5 (3) = 15

Solution is (3, 15)