Please do the bottom question. 5th grade math

What is the number 321,000,000 in scientific notation? also what is the number? ?

Which ratios are equivalent to 10: 16? check all that apply. 30 to 48 25: 35 8: 32 5 to 15

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?