a/0,1(6) = b/0,375
a/15/90 = b/375/1000
90a/15=1000b/375
6a = 8b/3
18a=8b
9a=4b⇒ b=9a/4
a+b= 20,8 ⇒a/1+ 9a/4= 208/10
4a/4+9a/4=208/10
13a/4=208/10
65a/20 = 416/20
65a=416
a= 6,4 dm =64 cm
b=20,8-6,4 = 14,4dm=144 cm
Inaltimea = √a*b= √64 * √ 144 = 8*12=96 cm=9,6 dm