20. A backpack that normally sells for $39 is on sale for 33% off. Find the amount of the discount and the sale price.
21. In August, the Simons' water bill was $48. In September, it was 15%
lower. What was the Simons' water bill in September?
22. A gallery owner purchased a very old painting for $3,000. The painting
sells at a 325% increase in price. What is the retail price of the
painting?

$26.13 sale price. $12.87 discount amount

Step-by-step explanation:

Discount is $39 * 33% (.33)= $12.87

Sale price is $39-$12.87=$26.13

< xcy ≅ < xby

step-by-step explanation:

in δcax and δbax,

so, δcax ≅ δbax (side-angle-side or sas)

since δcax ≅ δbax, we can conclude < acx ≅ < abx

in δacy and δaby,

so, δacy ≅ δaby (side-angle-side or sas)

since δacy ≅ δaby, we can conclude < acy ≅ < aby

now,

< acy ≅ < aby

=> < acx + < xcy ≅ < abx + < xby

=> < acx + < xcy ≅ < acx + < xby   (since < acx ≅ < abx already proved above)

subtracting < acx from both sides, we get

< acx + < xcy -< acx ≅ < acx + < xby -< acx

cancelling out < acx and -< acx from both sides, we get

< xcy ≅ < xby (proved)

b. f(x) = –√x + 3this is the correct answer