3б
(5а+10)^2-(5а-3)^2=132
25a^2+100a+100-(25a^2-30а+9)=132
25а^2+100a+100-25a+30a-9=132
130a+91=132
130a=132-91
130a=41
ответ: а=41/130
3б
(5а+10)^2-(5а-3)^2=132
25a^2+100a+100-(25a^2-30а+9)=132
25а^2+100a+100-25a+30a-9=132
130a+91=132
130a=132-91
130a=41
ответ: а=41/130