How do you find whether ratios are proportional

What is the length of the segment joining the points at (4,5) and (6,-2) round to the nearest tenth if necessary

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

Data from 2005 for various age groups show that for each $100 increase in the median weekly income for whites, the median weekly income of blacks increases by $105. also, for workers of ages 25 to 54 the median weekly income for whites was $676 and for blacks was $527. (a) let w represent the median weekly income for whites and b the median weekly income for blacks, and write the equation of the line that gives b as a linear function of w. b = (b) when the median weekly income for whites is $760, what does the equation in (a) predict for the median weekly income for blacks?