What is the missing number placed on the blue dot. Assignment from kahan academy

Cumulative examcumulative exam active13time remaining02: 44: 18the graph represents the data cost for monthly internetservice for a cell phone. which function, c(x), represents the monthly cost in dollarsin terms of x, the number of gigabytes used in a month? cell phone internet service(15,5x + 10150,0sx522 < x < 664x115, osx< 25x + 20, 2< x< 650, 65815%,monthly cost (s)20x + 5| 50x,0 < x < 22 < x < 664x( 15x, osx< 2c(x) = 5x + 10, 2< x< 6150x, 65 x5+1234 5 6 7 8 9 10 11 12gigabytes used

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6

What is the equation of a line passing through (-6,5) and having a slope of 1/3