A professor must randomly select 4 students to participate in a mock debate. There are 20 students in his class. In how many different ways can these
students be selected, if the order of selection does not matter?

One of the same side angles of two parallel lines is 20° smaller than the other one. find the measures of these two angles.

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?

Using elimination, what is -4x+2y=-12 4x+8y=-24