Match the following equation to the correct situation.

Question

20%(b − 21) = 20%b − 4.2
A.
An amount of chili was eaten from 20% of 4.2 less than b bowls.

B.
A number of songs are available for download from 20% of b artists.

C.
A number of cups of coffee were thrown away by 20% of b senators during 4.2 speeches.

D.
Last month's electricity bill was 4.2 kW-h less than 20% of this month's bill.

Answer 1

To match the equation \(20%(b - 21) = 20%b - 4.2\) to the correct situation, we can analyze both sides of the equation:

1. Left Side: \(20%(b - 21)\) implies taking 20% of \((b - 21)\), meaning a reduction from \(b\) by 21 before calculating 20%.

2. Right Side: \(20%b - 4.2\) suggests taking 20% of \(b\) and then subtracting 4.2.

Now let's evaluate the situations:

A. An amount of chili was eaten from 20% of 4.2 less than b bowls.

• This implies a calculation involving \(b - 4.2\), not directly matching the equation.

B. A number of songs are available for download from 20% of b artists.

• This scenario does not align with the equation since it doesn't involve any subtraction relating to 21 or 4.2.

C. A number of cups of coffee were thrown away by 20% of b senators during 4.2 speeches.

• This also does not fit as there’s no reference to subtraction or adjustments involving 21 or 4.2 in terms of percentages.

D. Last month's electricity bill was 4.2 kW-h less than 20% of this month's bill.

• This situation aligns most closely, as it discusses taking 20% of the current bill (comparable to \(b\)) and noting a reduction by 4.2 (just like the right side of the equation).

Thus, the correct match is: D. Last month's electricity bill was 4.2 kW-h less than 20% of this month's bill.