Salut!
[tex] \bf \: a)147 - {12}^{2} = [/tex]
[tex] \bf \: 147 - 144 = [/tex]
[tex] \bf \green{ \boxed{ \bf3}}[/tex]
[tex] \: [/tex]
[tex] \bf b) {13}^{2} + {11}^{2} = [/tex]
[tex] \bf \: 169 + 121 = [/tex]
[tex] \bf\green{ \boxed{ \bf290}}[/tex]
[tex] \: [/tex]
[tex] \bf c) {2}^{2} + {13}^{2} = [/tex]
[tex] \bf 4 + 169 = [/tex]
[tex] \bf \green{ \boxed{ \bf173}}[/tex]