Question

By what number should I multiply 1 1/4 by to obtain 3/4(fractions)

Answer 1

1 1/4x = 3/4
5/4x = 3/4
x = (3/4) / (5/4)
x = 3/4 * 4/5
x = 12/20 which reduces to 3/5

check..
1 1/4 * 3/5 =
5/4 * 3/5 =
15/20 reduces to 3/4 

so u would multiply 1 1/4 by 3/5 to get 3/4

Answer 2

I'd suggest dividing. so, what you do is you put 5/4 x 4/3 (thats how dividing works) and you get 20/12 which, when simplified, is 1 2/3.