21 and 22 pl i rlly needs (25p btw)

"Without using a calculator" suggests you are supposed to have memorized the square roots of 2 and 3 to at least 3 decimal places. That is, you know

21. √8 = √(2²·2) = 2√2 ≈ 2.83 . . . . about 4/5 of the distance between 2 and 3

22. √75 = √(5²·3) = 5√3 ≈ 8.66 . . . about 2/3 of the distance between 8 and 9

b. would be the answer : )

step-by-step explanation:

step 1: add -16x to both sides.

16x−4y+−16x=64+−16x  

−4y=−16x+64

step 2: divide both sides by -4.

−4y /-4 = -16x + 64/-4

answer:   y=4x−16

hope i'm right