Yes, set up your proportion: x/21 = 10/14
Cross multiply 14x = 210
Divide both sides by 14 and x= 15 cm
C= 5.5 I'm pretty sure that's the answer
d= 4.5 and c+ 5.5
Because 4.5 plus 1.0 = 5.5
since c is one more than d
5.5 plus 4.5 = 10
If the top is $48 and it is 60% off you will multiply the cost by the decimal form of the sale percentage: 48*0.60= $28.80. This is the amount she will save and I think is the answer you are looking for.
If there is a follow up question asking for the final cost of the top you would find that by subtracting the amount saved from the original cost: 48.00-28.80=$19.20.
Answer:
Mary and Duke have 3,172 stamps altogether
1,364 + 1,808 = 3,172
