Another way to put 6/7 - 1/8 is 48/56- 7/56 since the LCM of 7 and 8 is 56 (if you don’t know what that is I can explain it) sorta like subtraction you subtract both numerators (48 and 7 or 48-7) which gives you 41 then you put the denominator (56) below that. So in other words it equals 41/56