What if the teacher finds out?

What if the teacher finds out?

Chinese teachers often encourage me to read more books

The Chines teacher often encourages me to read more books

Can you tell me where the teacher's office is

Could you tell me where the teachers' office is?
I hope I can help you. I wish you a better future_ ∩)O
If you don't understand, please continue to ask (*^__ ^*)

-What is 0.5 - (- 3 and 1 / 4) + 2.75-7 and 1 / 2?
-How much is 1:2 1 × 7:5 - (- 7:5) × 2:2 1 + (- 2:1) × 5:7

-0.5 - (- 3 and 1 / 4) + 2.75-7 and 1 / 2
=-0.5+3.25+2.75-7.5
=-8+6
=-2
-1 and 2:1 × 7:5 - (- 7:5) × 2 and 2:1 + (- 2:1) × 5:7
=-3/2x5/4+5/7x5/2-1/2x5/7
=5/7x(-3/2+5/2-1/2)
=5/7x1/2
=5/14

To solve the equations: {2x + 5Y = 15m {5x-3y = - M

2x+5y=15m.(1)
5x-3y=-m.(2)
From (1) * 5 - (2) * 2, 31Y = 77m
So y = 77m / 31
Then substituting (2) to get x = 40m / 31

1998.8 + 198.8 + 19.8 + 9.8 + 0.8 (simple operation)

=2000-1.2+200-1.2+20-0.2+10-0.2+0.8
=2230-2.8+0.8
=2230-2
=2228

It is known that 4x2-mxy + 9y2 is the complete square of X and y, then the value of M is ()
A. 6B. ±6C. 12D. ±12

∵ (2x ± 3Y) 2 = 4x2 ± 12xy + 9y2, in 4x2 MXY + 9y2, M = ± 12

How to calculate 67 × 48 + 53 × 67-67 how to calculate 46 × 78 + 78 × 39-85 × 58

67×48＋53×67－67
=67×48＋53×67－67×1
=67×（48+53-1）
=67×100
=6700
46×78＋78×39－85×58
=78×(46+39)-85×58
=78×85-85×58
=85×（78-58）
=85×20
=1700

The cross section of a part is trapezoid, the area of cross section is 2.52 square decimeters, the height is 0.6 decimeters, and the length of the bottom is 4.2 decimeters longer than that of the top
How many decimeters are the top and bottom of this part?
There should be a formula,

Bottom: 6.3
Top bottom: 2.1

13x-x = 18.9

13x－x=18.9
(13－1)x=18.9
12x=18.9
x=1.575