(99 and 14 / 15) * 12

(99 and 14 / 15) * 12


=100*12-1/15*12
=1200-4/5
=1199 and 1 / 5



1 / 15 + 1 / 35 + 1 / 63 + 1 / 99 + 1 / 143?
There is not a third ahead


1 / 15 + 1 / 35 + 1 / 63 + 1 / 99 + 1 / 143
=(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)÷2
=(1/3-1/13)÷2
=10/39÷2
=5/39



1 / 15 + 1 / 35 + 1 / 63 + 1 / 99 + 1 / 143


1 / 15 + 1 / 35 + 1 / 63 + 1 / 99 + 1 / 143
=(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)÷2
=(1/3-1/13)÷2
=10/39÷2
=5/39