Simplify :

a) 25:35
b) 9/4:15/2
c) 8:18 to the form 1:n

a) 5:7

b) 18:35 or 36:70 (multiply both numerator and denominator by 2)
c) 4:9 (divide both terms by 2)

a) To simplify 25:35, you can divide both numbers by their greatest common divisor (GCD). The GCD of 25 and 35 is 5. Dividing both numbers by 5, we get:

25 ÷ 5 = 5
35 ÷ 5 = 7

So, 25:35 simplifies to 5:7.

b) To simplify 9/4:15/2, you can multiply the numerator and denominator of the first fraction by the reciprocal of the second fraction. The reciprocal of 15/2 is 2/15. Multiplying, we get:

(9/4) x (2/15) = (9 x 2) / (4 x 15) = 18/60

Both 18 and 60 can be divided by their GCD, which is 6. Dividing both numbers by 6, we get:

18 ÷ 6 = 3
60 ÷ 6 = 10

So, 9/4:15/2 simplifies to 3:10.

c) To express 8:18 in the form 1:n, you can divide both numbers by their GCD. The GCD of 8 and 18 is 2. Dividing both numbers by 2, we get:

8 ÷ 2 = 4
18 ÷ 2 = 9

So, 8:18 can be simplified to 4:9, which is in the form 1:n.