Just rewrite the sentences but instead of the italicized words put the ones in the parentheses
Yo como tacos.
Verbs in the present tense are typically conjugated in a pattern. They have specific rules and conjugations that have to be followed. Find the rules and you will succeed.
Yo- I
Tu- you
Usted- you guys
El- him
Ella- her
Nosotros- us
Ustedes- your
Ellos- they
Ellas- they
The correct demonstrative adjective for this sentences would be "este".
* Este niño en la foto es mi primo Francisco". Because "ESTE" refers to a singular male subject. If it would have been a girl, the correct option would have been "ESTA". For plurals we need to use "estos" and "esa" when it is a singular, female and we point the subject at a certain distance. "Esa es mi prima" --> That is my cousin (over there)