Alvin is 15 years older than Elga. The sum of their ages is 89. What is Elga's age?

Elga is 37 years old.

Step-by-step explanation:

Alvin (A) is 15 years older than Elga (E).

The sum their anges (A and E) is 89.

So the system we have is:

A=15+E

A+E=89

We are going to input 15+E for A in A+E=89 since first equation says A+15+E.

A+E=89 with A=15+E

(15+E) + E=89

15+E+E=89

15+2E=89

Subtract 15 on both sides:

2E=89-15

2E=74

Divide both sides by 2:

2E/2=74/2

E=74/2

E=37

Elga is 37 years old.

A=15+E=15+37=52 so Alvin is 52 yeard old.

52+37=89.

and

52=15+37.

Elga is 37 years old.

Step-by-step explanation:

Let 'x' be the age of elga.

Alvin's age is: x + 15

Given that the sum of their ages is 89, we have that:

x + 15 + x = 89

2x = 89 - 15

2x = 74

x = 74/2 = 37

Elga is 37 years old.