jawablah dengan benar beserta caranya untuk banyak point

1) ( 5p + 7)(4p - 5)
= 20p² + 28p² - 25p - 35
= 20p² + 3p - 35

2) ( 8xy² + 2x )
-----------------------
4y

= 2(4xy² + x )
-------------------
2 ( 2y)

= 4xy² + x
----------------
2y

= x ( 4y² + 1)
-------------------
2y

3) ( x+4 / 7 ) ÷ ( x-8 / 4)

= ( x + 4 ) × ( 4 )
-----------------------
( x - 8 ) × ( 7)

= 4x + 16
--------------
7x - 56

4) 20a³b² = 2² × 5× a³ × b²
16ab⁴ = 2⁴ × a × b⁴
fpb = 2² × a × b² = 4ab²
kpk = 2⁴ × 5 × a³ × b⁴ = 80a³b⁴

5) K = 2 × ( p + l )
32 = 2 ×{ (3x + 2) + ( 2x - 1)}
32 = 2 × ( 5x + 1)
5x + 1 = 32 ÷ 2
5x + 1 = 16
5x = 16 - 1
5x = 15
x = 3
lebar = 2x - 1 = 2(3) - 1 = 5 cm