Simple calculation: 9 and 15 / 4 + 3 and 5 / 3 × 4 and 12 / 1 △ 2 and 3 / 1

Simple calculation: 9 and 15 / 4 + 3 and 5 / 3 × 4 and 12 / 1 △ 2 and 3 / 1

9:15:4 + 3:5:3 × 4:12:1 △ 2:3:1
=9+4/15+18/5×49/12÷(7/3)
=9+4/15+18/5×49/12×3/7
=9+4/15+63/10
=9+8/30+6+9/30
=15 and 17 / 30

Simple calculation process: (5 / 12 + 3 / 8) × 8 / 15

（5/12+3/8）x8/15
=5/12x8/15+3/8x8/15
=2/9+1/5
=19/45

1（ ）2（ ）3（ ）4（ ）5=60

(1×2^3+4)×5=60

The price of a color TV set is 2430 yuan after two consecutive price cuts of 105%?

Two price cuts of X% at 2430,
The original price of this color TV set is 2430 / (1-x%) / (1-x%) yuan
If the price is reduced by 10% twice, the original price is 2430 / (1-10%) / (1-10%) = 3000 yuan

2010+2009*1999/2010*2000-1999

2010+2009*1999/2010*2000-1999=[2010+(2010-1)*1999)]/(2010*2000-1999)=(2010+2010*1999-1999)/(2010*2000-1999)=[2010(1+1999)-1999]/(2010*2000-1999)=(2010*2000-1999)/(2010*2000-1999)=1

The number of regularly arranged columns: 2, 4, 6, 8, 10, 12 Each term can be expressed by the formula 2n (n is a positive integer). The number of regularly arranged columns: 1, - 2, 3, - 4, 5, - 6, 7, - 8
(1) What formula do you think can be used to express each of its terms?
It's better to write down the process,

n×（－1）^（n+1）

What does wire 3 * 75 + 2 * 50 mean

The key is what the front mark is. What you're talking about now is. Three 75 outer diameter wires and two 50 outer diameter wires. This kind of wires does not belong to conventional wires. Conventional wires are 3 * 70 + 1 * 35. This kind of wires also have many kinds. Sheath, crosslinking, fire resistance and flame retardant. Exception: the front four kinds of wires all have Kai. The mark is vv22.yjv22.zcn-yjv22 cz-yjv22
Hope to help you

Expressed by scientific notation -0.00 000 032=______ ．

-0.00 000 032 = - 3.2 × 10-7. So the answer is: - 3.2 × 10-7

How should I end my good friend

She (he) - my good friend, although is an ordinary student, but TA in my eyes, is the best
If it's about friends doing good, you can write like this

As shown in the figure, in rectangular ABCD, ab = 12cm, BC = 6cm, points E and F are on AB and CD respectively. Fold rectangular ABCD along EF so that points a 'and d' fall on points a 'and d' on the outside of rectangular ABCD respectively, then the perimeter of the whole shadow part figure is ()
A. 18cmB. 36cmC. 40cmD. 72cm

Extend a1e and intersect CD at point g. from the meaning of the title, Ge = eh, FH = GF, ehd1a1 ≌ EGDA, ad = a1d1, AE = a1e, DG = d1h, FH = FG, the perimeter of the shadow part = the perimeter of the rectangle = (12 + 6) × 2 = 36cm