How to solve 3.16 times 10 to the 3rd power

Lin is writing an equation to model the proportional relationship between y, the total cost in dollars of downloading videos from a website, and x, the number of videos downloaded. she knows that the total cost to download 3 videos was $12. her work to find the equation is shown below. joylin’s work step 1 k= 3/12= 0.25 step 2 y= 0.25x where did joylin make her first error?

*let m∠cob = 50°30’, m∠aob = 70° and m∠aoc = 20°30’. could point c be in the interior of ∠aob? why?

Given sin∅ = 1/3 and 0 < ∅ < π/2 ; find tan2∅ a. (4√2)/9 b. 9/7 c. (4√2)/7 d.7/9