The numbers are in batches of 3. The series is formed by multiplying the first number by 3 then dividing the product by 2.
10 x 3 = 30 : 30 ÷ 2 = 15
16 x 3 = 48 : 48 ÷ 2 = 24
25 x 3 = 75 : (75 ÷ 2 = 37.5)
The number required is 75
10 x 3 = 30 : 30 ÷ 2 = 15
16 x 3 = 48 : 48 ÷ 2 = 24
25 x 3 = 75 : (75 ÷ 2 = 37.5)
The number required is 75