B=24:100*A=0.24*A
B=C+7
C=16:100*A
B=0.24*A
C=0.16*A
B=C+7
B=0.24*A
C=0.16*A
0.24*A=7+0.16*A
B=0.24A
C=0.16A
A*(0.24-0.16)=7
0.08*A=7
B=0.24*A
C=0.16*A
A=87.5
B=0.24*87.5=21
C=0.16*A=14
ответ: B=21
(2а-5b)(2a-5b) - (a+2b)(2a-5b)
(2a-5b)*((2a-5b)-(a+2b))