formula to calcualte number based on several factors

Hi,

I am sort of new to excel and not so great with using the if and then function so any help would be appreciated.

looking for a formula to do this:

if the number(x) is less than 4 then do 15 + (x*7.25), if (x) is larger than 4 but less than 8 then 15 + (x*6), if (x) is larger than 8 but less than 14 then 15 + (x*4) and if (x) is larger than 14 then 15 + (x*3)



thank you

not to be a pain but i just remembered the last part :

i would need this formula to be ale to add 30 to the end result if the cell contained a number with 07 in it

example:

column a column b column c column d
11111 22222 5 50
07222 22222 5 should be 80