How many 2-digit numbers are multiples of 5 but not 4?

Quick 14
Remark
The numbers you are describing can end in 5. But there are others as well. They are  t = 10 + 20*n where n goes from 0 to 4. So if n is 4 that means that t = 4*20 + 10 = 80 + 10 = 90. 

Solution
15 25 35 45 55 65 75 85 95 are all divisible by 5 but not  4 
10 30 50 70 90                     are all divisible by 5 but not 4