A number 2 / 5 is 36 more than 45% of 120. Find this number

A number 2 / 5 is 36 more than 45% of 120. Find this number

This number is X
2x/5-120*45％=36
2x/5-54=36
2x/5=90
x=5*45=225

A number of 2.5 times, 13.5 times less than his 7 times, how much is this number? (use equation solution) Yes, come on!
A number of 2.5 times, 13.5 times less than his 7 times, how much is this number? (use equation solution) Yes, come on!

7X-2.5X=13.5
4.5X=13.5
X=3

If the length of a rectangle is reduced by 5cm, the area will be reduced by 20cm. If the width is increased by 3cm, the area will be increased by 30cm. What is the area of the original rectangle?

If the length of a rectangle is reduced by 5cm, the area will be reduced by 20cm, so its width is 4cm
If the width is increased by 3 cm, the area is increased by 30 square cm, and its length is 10 cm
Therefore, its original area is 40 cm and 178 cm;

In △ ABC, a is the minimum angle, B is the maximum angle, and 2 b = 5 A. if the maximum value of B is m ° and the minimum value is n °, then M + n=______ ．

∵ 2 ∠ B = 5 ∠ a, i.e. ∵ B = 52 ∠ a, ∵ C = 180 ° - A - ∠ B = 180 ° - 72 ∠ a, and ∵ a ≤ ∠ C ≤ ∠ B, ∵ a ≤ 180 ° - 72 ∠ a, i.e. ∵ a ≤ 40 °; and ∵ 180 ° - 72 ∠ a ≤ 52 ∠ a, i.e. ∵ a ≥ 30 °, and ∵ 30 °≤ ∠ a ≤ 40 °, i.e. ∵ 30 °≤ 25 ∠ B ≤ 40 °, and ∵ 75 °≤

1. A metal with a mass of 10G is taken out from the boiling water at 100 ° C and quickly put into the cold water with a mass of 30g and an initial temperature of 25 ° C. the final temperature after mixing is measured to be 30 ° C, regardless of heat loss
(1) How much heat does cold water absorb?
(2) What is the specific heat capacity of this metal block?
2. It needs 9.6225 × 10 ^ 5J heat to put some water into the special pass with a mass of 500g and heat it from 15 ° C to 90 ° C. please put forward three questions according to the above conditions,
(cwater = 4.2 × 10 & sup3; J / (kg, ℃), cferre = 0.46 × 10 & sup3; J, (kg, ℃)
The second question is too fast
2. In a 500g iron pot

1、（1）630J.（2）0.9×10³J/(kg,°C）
2、……

Use a 12.56 long wire to circle a square, and then form a circle. What is the area of the circle, so whose area is the largest when the perimeter is equal

Square side length 12.56 / 4 = 3.14 area 3.14 ^ 2 = 9.8596
The diameter of the circle is 12.56 / 3.14 = 4, the radius is 2, and the area is 2 ^ 2 * 3.14 = 12.56
So it's round and big

Find the value of the power n of 2 + the power n of 2 - the power 2n + 1 of 2! I need it urgently!

2^(2n+1)=8
2^(2n+1)=2^3
2n+1=3
n=1
(n-2)^(2010+n)
=(1-2)^2011
=(-1)^2011
=-1

Mathematical calculation problems (easy)
Speed is the answer to these three questions, with (or without) process speed!,
1.-4+（-8）×5-（-0.28）×0.25
2.0-4÷（-2）+0-8÷（-8）
3.（1/3-3+1/6-7/12）×36

1.-44.07
two point three
3.-111

A cylinder with a height of 5 cm is sawed into two pieces along the diameter of the bottom surface, and its surface area is increased by 40 square centimeters. The original volume of the cylinder is much larger
What's the volume and surface area of this cylinder?
To be accurate!!!! Hurry!

40 / 2 / 5 = 4cm (bottom diameter)
4 / 2 = 2 cm (bottom radius)
3.14 * 2 * 2 = 12.56 square centimeter (bottom area)
12.56 * 5 = 62.8 cm3 (volume)
3.14 * 4 = = 12.56 cm (bottom perimeter)
12.56 * 5 = 62.8 square centimeter (side area)
12.56 * 2 + 62.8 = 87.92 square centimeter (surface area)

Light year is the unit of distance in astronomy. One light year is about 9 & nbsp; 500 & nbsp; 000 & nbsp; 000 & nbsp; 000 km, which can be expressed as______ ．

9 500 000 = 9.5 × 1012, so the answer is: 9.5 × 1012km