幫忙下數學題列式

23)
The length of the fence
= 4 x √441
= 84 m

24)
The area of the margin
= (50 + 1)² - 50²
= 101 m²

25)
% of journey she hasn't finished
= 1 - 15% - 33%
= 52%
The total distance of the journey
= 260 / 52%
= 500 km

23) A square vegetable field has an area of 441 m2 . It is surrounded by a fence. Find the length of the fence.
Let a meters be the length of the fence.
Given area of field = 441 m^2
Thus, length of one side of the fence
= √ 441
=21
Therefore , length of fence, a
=21 * 4
= 84 (meters)

數學題列式:
a = √ 441 * 4
= 84 (meters)


24) The side of a square field is 50 m. It is planted with flowers, leaving a margin of 1 m wide all round. Find the area of the margin.
Let a meters be the length of the margin;
Thus the area of the margin = a^2 sq. meters
Given the length of one side of a square field = 50 m.
Thus, the area of field (without flower margin) = 50 ^2 sq. m.
Also, the length of one side of field (with margin) = 50 + 2 m.
Thus, the area of field (with flower margin) = (50 + 2) ^ 2 sq. m.
Area of margin, a
= (50 + 2) ^ 2 - 50 ^2
= 204 (sq. m.)

數學題列式:
a = (50 + 2) ^ 2 - 50 ^2
= 204 (sq. m.)




25) After coveing 15% of the journey in the morning and 33% of it in the afternoon, Amy found that she still had 260km left. Find the total distance of the journey.
Let a km. be the total distance of the journey.
a - 15%a - 33%a = 260
52% a = 260
a = 500 (km.)

數學題列式:
a = 260 * 100 / (100 - 15 - 33)
= 500 (km.)

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