Can 1 minus 6 / 7 divide by 2 minus 4 / 7

Can 1 minus 6 / 7 divide by 2 minus 4 / 7

1-6/7÷2-4/7
=1-3/7-4/7
=1-(3/7+4/7)
=1-1
=0

Please ask, 6 divided by [] = 1 / 7
reason.. thank you

Simple, 6 divided by [42] = 1 / 7

A simple method for finding determinant 246 427 327 | 1014 543 443 | - 342 721 621

C1 + 2c3, C2-C3 900 100 3271900 100 443 900 100 621r2-r1, r3-r1 900 100 3271000 0 116 0 0 294 c1-9c2 0 100 3271000 0 116 0 0 294 the determinant = - 29400000 can be obtained from the definition of diagonal rule or determinant

What's the simple method of 885 + 886 + 887 + 888 + 889

885+886+887+888+889
= 887 ×5
= 4435

Can 1 / 12 + (11 / 12-5 / 6) be simplified
Do you have 17 / 21-5 / 13 + 25 / 21-8 / 13K for easy operation

Original formula = (1 / 12 + 11 / 12) - 5 / 6
=1-5/6
=1/6
Original formula = (17 / 21 + 25 / 21) - (5 / 13 + 8 / 13)
=2-1
=1

As shown in the figure, in △ ABC, ∠ 1 = 100 °, ∠ C = 80 °, ∠ 2 = 12 ∠ 3, be bisects ∠ ABC. Calculate the degree of ∠ 4

∵∠ 1 = ∠ 3 + ∠ C, ∵ 1 = 100 °, ∵ C = 80 °, ∵ 3 = 20 °, ∵ 2 = 12 ∠ 3, ∵ 2 = 10 °, ∵ ABC = 180 ° - 100 ° - 10 ° = 70 °, ∵ be bisection ∠ BAC,