Ex. 8
a÷x+b÷x=20 => (a+b)÷x=20
a+b=40 40÷x=20 => x=40÷20=2
Ex. 10
a.) 2ab- suma cifrelor 10
10-2=8 => a+b=8
...de aici trebuie sa iei toate combinatiile posibile de ex: a=1 , b=7
b=7, a=1
b.) ab=ba
11=11
22=22
33=33
44=44
55=55 => 9 nr
66=66
77=77
88=88
99=99
Ex. 11
x-y=27 si z=3
a.) (x-y)⁵÷z¹³=27⁵÷3¹³
27= ( 3³)⁵=3¹⁵
Avem 3¹⁵÷3¹³=3²=9
b.) x×z-y×z =(x-y)×z=27×3=60+21=81
c.) x÷z³-y÷z³ = (x-y)÷z³=27÷3³=27÷27=1
