I'm new at this. Can anybody tell me how to do a formula for the following:

If A3,A4,A5,A6,A7 =0, B10=0
If A3 or A4 ="X", B10 =B2*3
If A5 or A6= "X", B10 = B2*4
If A7 = "X", B10 = B2*5