Elena and her grandfather both just had birthdays last week. The sum of their ages is 100 years. Her grandfather’s age is 4 times Elena’s age. How old are Elena and her grandfather?

Grandfather age = 20 * 4 = 80

Step-by-step explanation:

Let Elena age be x

grandfather age is 4x

x + 4x = 100

5x = 100

x = 100/5 = 20 = Elena age

use distributive property on all like terms and change your signs if you have a double negative or if you have positive/negative

it has to have an angle of 90 degrees