18/42=3/7

45/65=9/ 13

So 45/65 is very big.

There is a pile of chemical fertilizer, 3 tons used, and 12 tons left. How much is this pile of fertilizer used?

3÷( 12+3)= 1/5

The simplest fraction converted from a fraction is 5/8, and the denominator of the original fraction is 30 larger than the numerator. What is the numerator of the original fraction?

Let the denominator x be X-30.

(x-30)÷x=5/8

8x-240=5x

3x=240

x=80

80-30=50

The original partial molecule 50