6x+11=21 i dont know what x is! Help me plz

The formula for the lateral area of a right cone is la = rs, where r is the radius of the base and s is the slant height of the cone.which are equivalent equations?

How do i simply this radical expression?

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?