Amy spends 1/3 of her time working on math and 1/4 working on science. How much time does she spend on history?

0 because nobody like history

jk

assuming that she spends all of her time on those 3 subjects

all-math-science=history

all=1

1-1/3-1/4=history

make bottom number same

3*4=12, so bottom number has to be 12

1/3*4/4=4/12

1/4*3/3=3/12

1=12/12

12/12-4/12-3/12=history

(12-4-3) / 12=history

(12-7) / 12=history

5/12=history

spends 5/12 of her timem on history