Because #640s# is the relationship between #s# square miles and acres, so :
#color(green)(a= 640)#
#color(green)(s=7.5)# square miles.
(*Since Pam owns #color(blue)7.5# square miles, so #color(blue)7.5# becomes #color(red)s .#)
Therefore, we would do:
#color(red)(640*7.5)#
Because when a number is with a variable(#color(purple)(640s#), this means it's #color(purple)640# times the variable. So for this case it would be : (as #color(magenta)7.5# is #color(red)s#)
#color(orange)(640 * s = 640*7.5 = 4800) # acres
So Pam owns #color(blue)(4,800)# acres.
