Can anyone help me solve these problems?

I don't know what functions to use....PLEASE HELP!
1. Enter a conditional function in cell M4 to calculate the total membership fees paid by members 25 years old or younger.
2. Enter a similar function in cell M5 to calculate the total number of membership fees paid by members over the age of 25. Format the results in M4 and M5 with Accounting Number Format.
3. Enter a similar function in cell L10 that calculates the total number of members over the age of 25 that lost at least 5 pounds.
4. Enter a function in cell H4 that calculates the rank of the weight loss in cell G4 against the range of individual weight lost in the data set.
Use the fill handle to copy the function down column H. Be sure to include the appropriate absolute or mixed cell references before copying the functions.

THANKS TO ANYONE WHO CAN HELP!!!!!

How about an IF formula that looks at the value of the age field to then determine a calc. for example IF(m3>25,2400,0) where m3 is the age. Similarly you could use the same function types in the other examples.

So, I would put (c4:c53>25, and what would I put under 2400?