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?

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

This is so hard and it’s for a test

Graph y ≥ -x^2 - 1. click on the graph until the correct graph appears.