3 weeks = 3*7 = 21 days
(46 arrangements)/(3 days) = (x arrangements)/(21 days)
46/3 = x/21 is one possible proportion to set up
Let's solve for x.
46/3 = x/21
46*21 = 3x
3x = 46*21
x = 46*21/3
x = 46*7
x = 322 floral arrangements can me be made in 3 weeks. This assumes the florist keeps the same rate.