Please help this is due tomorrow!! angel is Eight years younger than his brother Alex together their total age in years is 30. select two equations of a system that can be solved to find both ages

x+y=30

x-y=30

x+y=8

x-y=8

How many years old is angel?

How many years old is Alex?

Ameteorologist is studying the monthly rainfall in a section of the brazilian rainforest. she recorded the monthly rainfall, in inches, for last year. they were: 10.4, 10.3, 11.7, 11.1, 8.0, 4.4, 2.6, 1.8, 2.5, 4.4, 7.3, 9.5 fill in the missing values in the formula. what is the variance?