Here's what we're given:
1 lb strawberries = $6.59 (where the cost equals price × lb)
1 lb watermelon = $3.27 (where the cost equals price × lb)
c = combined cost (this is what we're looking for)
c = cost of strawberries + cost of watermelons
Going by the definition of strawberries' and watermelons' costs (cost is price times pounds), replace with variables.
c = (2 × $6.59) + (4 × $3.27)
c = 13.18 + 13.08
c = 26.26
c = $26.26