An oil painting is twice as long as it is wide. I used a 1.8m wooden frame. What is the length, width and area of this painting?

An oil painting is twice as long as it is wide. I used a 1.8m wooden frame. What is the length, width and area of this painting?

Let the width of the frame be x meters, then the length is 2x meters. According to the formula of the circumference of the rectangle, we can get: (x + 2x) × 2 = 1.8, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 6x = 1.8, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 0.3, 2 × 0.3 = 0.6 (m), 0.3 × 0.6 = 0.18 (M2). A: the length of this painting is 0.6 m, the width is 0.3 m, and the area is 0.18 m2

When a number is reduced by 20%, it is exactly 50% of 80. What is the number of equations

Let this number be X
x（1-20%）=80×50%
0.8x=40
x=50
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80% of a number is 20. What's its 30%

0.8X=20
X=25
25*0.3=7.5

30 minus 80 percent is 20; what's the answer

This number is X
30-80%x=20
0.8x=30-20
0.8x=10
x=12.5