Question

450 пж помогите лвлаоаоалв

Answer 1

1) 1/2+2/5= 5/10+4/10=9/10
2) 1/2-2/5=5/10-4/10=1/10
3) 1/4+1/6=3/12+2/12=5/12
4) 9/10-5/6=27/30+25/30=52/30=26/15=1. 11/15