2g + 69
Since 3g and g has the same variable: g, you can directly evaluate their co-efficients: 3 and 1.
3g - g = (3-1)g
Creo que eso es lo quieres
Last one, triangles AOB and COD
In step 3, they are talking about the side/angle/side postulate. That helps in describing a triangle, therefore she must be talking about a triangle