Which expression completes the following equation? 3 × 31 = a. 31 × 3 b. 31 - 3 c. 31 ÷ 3 d. 31 + 3

How to do this , and can some one explain

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?

What three-dimensional solid have 6 rectangular faces, 2 equal bases that are not rectangles and 18 edges