hi jesuroselin. assuming your data is in A1:D1, try:
=IF(COUNTIF(A1:D1,">70")>=3,15,IF(COUNTIF(A1:D1,">60")>=3,13,IF(AND(SUMPRODUCT((A1:D1>50)*(A1:D1<60))=2,COUNTIF(A1:D1,"<50")=2),11,IF(COUNTIF(A1:D1,">=50")=1,10,5))))