Answer:
The correct form of the adjective, in each case, is
1. La abuela es <u>vieja</u>.
2. La abuela es <u>trabajadora.</u>
Explanation:
In Spanish, an adjective could be in two forms:
1. Gender.
- Male.
- Female.
2. Number.
- Singular.
- Plural.
This forms can be combined: singular female <em>(vieja, trabajadora),</em> singular male <em>(viejo, trabajador)</em>, plural female <em>(viejas, trabajadoras)</em>, plural male <em>(viejos, trabajadores)</em>, then, now you know what is the correct form in each case, you must see the form of the substantive: "abuela" is a substantive singular and female, for that reason, you must use the forms "vieja, trabajadora".