Please help me find an equation for this

The equation that represents this situation is x + 3x + (x - 4) + 2(x - 4) = 72, where x is Erik's age

Step-by-step explanation:

Let us solve the question

Assume that Erik is x years old

∵ Erik is x years old

∵ Erik is as old as Dawn

→ That means x = Dawn

∴ x = Dawn

→ Multiply both sides by 3

∴ 3x = Dawn

∴ Dawn is 3x years old

∵ Jiro is 4 years younger than Erik

→ That means Jiro = x - 4

∴ Jiro is (x - 4) years old

∵ Alita is 2 times as old as Jiro

→ That means Alita = 2 × (x - 4)

∴ Alita = 2 × (x - 4)

∴ Alita is 2(x - 4) years old

∵ The sum of all their ages is 72

→ That means add their ages and equate the sum by 72

∴ Erike's age + Dawn's age + Jiro's age + Alita's age = 72

∴ x + 3x + (x - 4) + 2(x - 4) = 72

The equation that represents this situation is x + 3x + (x - 4) + 2(x - 4) = 72, where x is Erik's age

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18