To find out how much $6 plums will cost, first ask, "How much does each plum cost?"
We can figure that out by dividing the cost of 4 plums by 4. We know that 4 plums cost $5.50.
5.50 ÷ 4 = 1.375.
Each plum has a value of $1.375,
1.375 x 6 = $8.25
Your answer: Six plums will cost $8.25 (Expensive, but delicious!) :-)