Suatu persegi panjang berukuran panjang (2a+5) meter dan lebar (2a-1) meter. jika kelilingnya 32 meter, maka:

A. keliling = 2 (p+l)
32 = 2 (2a+5) + 2 (2a-1)
32 = 4a + 10 + 4a – 2
32 = 8a – 8
8a = 32 – 8
8a = 24
a = 24 : 8 = 3

b. panjang = 2a+5 = 2.3 + 5 = 11m
    lebar = 2a-1 = 2.3-1 = 5m

A. 2(2a+5+2a-1=32
4a+10+4a-2=32
4a+4a+10-2=32
8a+8=32
8a=32-8
a=24/3
a=3
lebar=2a-1
=2.3_1
=6-1=5
panjang =2a+5
=2.3+5
= 11