Question

Таня ест пирожок. после первого откусывания масса пирожка уменьшилась на 20 %, после второго откусывания, масса уменщилась еще на 20 % и стала 128 грамм. сколько весил пирожок вначале?

Answer 1

После второго откусываемая:пропорции
80%-128
100%-х
Х=160 грамм весил пирожок до второго откусываемая откусывания

После первого откусывания пропорции:
80%-160
100%-х
Х=200 грамм весил целый пирожок

Answer 2

1)128 х 100 : 80 = 160 (гр) - весил пирожок после первого укуса
2) 160 х 100 : 80 = 200 (гр) - весил пирожок

Answer 3

Problem Analysis

We are given that Tanya eats a pie, and after the first bite, the mass of the pie decreases by 20%. After the second bite, the mass decreases by another 20% and becomes 128 grams. We need to determine the initial weight of the pie.

Solution

Let's assume the initial weight of the pie is x grams.

After the first bite, the mass of the pie decreases by 20%, which means it becomes 0.8x grams.

After the second bite, the mass decreases by another 20%, which means it becomes 0.8 * 0.8x grams, or 0.64x grams.

We are given that the mass after the second bite is 128 grams, so we can set up the equation:

0.64x = 128

To find the value of x, we can divide both sides of the equation by 0.64:

x = 128 / 0.64

Evaluating the right side of the equation:

x = 200

Therefore, the initial weight of the pie was 200 grams.

Answer

The initial weight of the pie was 200 grams.