If (3a + 3b + 1) (3a + 3b - 1) = 80, then what is a + b?

a + b = 3 -       maybe

Step-by-step explanation:

( 3a + 3b + 1 )( 3a + 3b - 1 ) = 80

Expand

9a² + 9ab - 3a + 9ab + 9b² - 3b + 3a + 3b - 1 = 80

Simplify

9a² + 9b² + 18ab - 1 = 80

move the 1 over

9a² + 9b² + 18ab = 81

divide by 9

a² + b² + 2ab = 9

not really sure after this part

move the 2ab over

a² + b² = 9 - 2ab

square root both sides

a + b =

simplify

a + b = 3 -

solution:

as, mean is defined as sum of all the observations divided by total number of observations.

and , median is mid value of the data whether arranged in ascending order or descending order.

consider, roadsters:

2,3,4,5,6,7,8,9

mean =

also, median= , because number of observations is even, so median is mean of two mid values.

now, coming to bandits

2,3,4,5,6

mean =  

median = 4, as number of observations is odd.

so, roadsters has greater median as well mean than bandits.

→option a is true about the repairs performed on 2 types of cars:

bandits have lower median and mean than roadsters.

2.2°  

step-by-step explanation:

let θ = the angle of elevation.

tanθ =77/2020

tanθ = 0.038 12

      θ = tan⁻¹0.038 12

      θ = 2.2°