Which shows 42^2 − 38^2 being evaluated using the difference of perfect squares method?

a) 42^2 − 38^2 = (1,764 − 1,444)(1,764 + 1,444) = 1,026,560
b) 42^2 − 38^2 = 84 − 76 = 8
c) 42^2 − 38^2 = (42 − 38)^2 = (4)^2 = 16
d) 42^2 − 38^2 = (42 + 38)(42 − 38) = (80)(4) = 320

The cost varies directly with the number of tickets purchased. it costs $145 for 10 people to attend a concert. a. what is the constant of proportionality (k)? b. write the direct variation equation. c. home much does it cost for 8 people? d. graph this situation. be sure to label each axis and give the graph a title.