Alvin's age is two times Elga's age. The sum of their ages is 72. What is Elga's age?

Alvin 46, Elga 23

Step-by-step explanation:

So you set up two equations:

Before anything lets assume

age of Elga = E

age of Alvin = A

Then,

A = 2E (Alvin's age is 2x Elga's age) (EQ 1)

A+E=72 (Sum of Alvin's and Elga's age) (EQ 2)

Plug the value of A from eq1 to eq2.

A+E=72

2E+E=72 (we plugged here the value of A from eq1)

3E=72

E = 26 (Elga's Age)

Now solve for Alvin's age by plugging E in either equation:

A+E=72

A+26=72

A = 46yr (Alvin's Age)

or Plug in eq 1

A=2E

A = 2x23 = 46yr (Alvin's Age)