Keeping in mind that, the segment is split in three thirds, and the point is 2/3 of the way, so is closer to (9, -2), with a 2:1 ratio, check the picture below.
Ok so the Markup is how much money you will add on the price so it's 15% of $18 and you don't need to add it onto $18
The Retail Price is the entire price so the retail would be the Markup + Price.
15% of $18 is is $2.7 and $18 + $2.7 is $20.7
its 8.7 since a tenth is the number after the . so 8.68 take 68 whats the nearest multiple of ten 70 so 8.7
let the first angle be a
then
second angle= 68+a
third angle=2a
we know
a+b+c=180 [sum of interior angle of triangle is 180]
a+68+a+2a=180
4a=180-68
a=28
Hence
first angle=28
second angle = 96
third angle =56