Write the number 9.91•10-6 in standard notation.
O 0.0000991
O 9,910,000
O 0.00000991
O 0.000000991

$18 was the price of the t-shirt

step-by-step explanation:

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.

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°