[tex] a)\frac{2x+2}{28}= \frac{5}{7} \\ \\ 7(2x+2)=5*28 \\ \\ 14x+14=140 \\ \\ 14x=140-14 \\ \\ 14x=126 \\ \\ x=9 \\ \\ b)\frac{3x+2}{35}= \frac{4}{7} \\ \\ 7(3x+2)=4*35 \\ \\ 21x+14=140 \\ \\ 21x=140-14 \\ \\ x=126:21 \\ \\ x=6 \\ \\ c)[tex] \frac{2x^{2}-14 }{108}= \frac{2}{6} \\ \\ 6(2 x^{2} -14)=2*108 \\ \\ 12 x^{2} -6*14=216 \\ \\ 12 x^{2} =216+84 \\ \\ 12 x^{2} =300 \\ \\ x^{2} =300:12 \\ \\ x^{2} =25 \\ \\ x=5[/tex]
[tex]d) \frac{51}{ x^{2} +38} = \frac{3}{7} \\ \\ 7*51=3( x^{2} +38) \\ \\ 357=3 x^{2} +3*38 \\ \\ 357-114=3x^{2} \\ \\ 243=3 x^{2} \\ \\ x^{2} =243:3 \\ \\ x^{2} =81 \\ \\ x=9[/tex]
